WO2007008144A1 - Heterocyclic sulfonamide derivatives as inhibitors of factor xa - Google Patents

Abstract

The invention relates to compounds of formula (I), Chemical formula should be inserted here. Please see paper copy wherein R1 is hydrogen, C1-3alkyl, R5R6 aminoC1-5alkyl, where R5 and R6 are each independently selected from hydrogen and C1-3alkyl, or R5 and R6 may, together with the nitrogen to which they are attached, form a five- or six-membered heterocyclic ring, where said heterocyclic ring has 0 or 1 additional heteroatom; n is 1 or 2; each R2 are independently selected from hydrogen, oxo and C1-3alkyl, R3 is an indolyl, and R4 a hydrogen or a halogen; or a pharmaceutically acceptable salt thereof, said compounds possess antithrombotic and anticoagulant properties and are accordingly useful in methods of treatment of humans or animals. The invention also relates to processes for the preparation of the compounds, to their use, to pharmaceutical compositions comprising them, to their use in the manufacture of medicaments for use in the production of an antithrombotic or anticoagulant effect, and to combinations comprising them.

Description

HETEROCYCLIC SULFONAMIDE DERIVATIVES AS INHIBITORS OF FACTOR Xa

The invention relates to novel heterocyclic derivatives, or pharmaceutically-acceptable salts thereof, which possess antithrombotic and anticoagulant properties and are accordingly useful in methods of treatment of humans or animals. The invention also relates to processes for the preparation of the heterocyclic derivatives, to their use, to pharmaceutical compositions comprising them, to their use in the manufacture of medicaments for use in the production of an antithrombotic or anticoagulant effect, and to combinations comprising them.

The antithrombotic and anticoagulant effect produced by the compounds of the invention is believed to be attributable to their strong inhibitory effect against the activated coagulation protease known as Factor Xa. Factor Xa is one of a cascade of proteases involved in the complex process of blood coagulation. The protease known, as thrombin is the final protease in the cascade and Factor Xa is the preceding protease, which cleaves prothrombin to generate thrombin.

Certain compounds are known to possess Factor Xa inhibitory properties and the field has been reviewed by B. -Y. Zhu, R. M. Scarborough, Current Opinion in Cardiovascular, Pulmonary & Renal Investigational Drugs, 1999, 1(1), 63-88. Thus it is known that two proteins, one known as recombinant antistasin (r-ATS) and the other known as recombinant tick anticoagulant protein (r-TAP), are specific direct Factor Xa inhibitors which possess antithrombotic properties in various animal models of thrombotic disease. It is also known that certain non-peptidic compounds possess Factor Xa inhibitory properties. Of the .low molecular weight inhibitors mentioned in the review by B.-Y. Zhu and R. M. Scarborough, many inhibitors possess a strongly basic group such as an amidinophenyl or amidinonaphthyl group.

We have now found that certain heterocyclic derivatives possess Factor Xa inhibitory activity. Many of the compounds of the present invention also possess the advantage of being selective Factor Xa inhibitors, that is the enzyme Factor Xa is inhibited strongly at concentrations of test compound which do not inhibit or which inhibit to a lesser extent the enzyme thrombin which is also a member of the blood coagulation enzymatic cascade.

The compounds of the present invention possess activity useful in the treatment or prevention of a variety of medical disorders where anticoagulant therapy is indicated, for example in the treatment or prevention of thrombotic conditions such as coronary artery and cerebrovascular disease. Further examples of such medical disorders include various cardiovascular and cerebrovascular conditions such as myocardial infarction, the rupture of atherosclerotic plaques, venous or arterial thrombosis, coagulation syndromes, vascular injury including reocclusion and restenosis following angioplasty and coronary artery bypass surgery, thrombus formation after the application of blood vessel operative techniques or after general surgery such as hip replacement surgery, the introduction of artificial heart valves or on the recirculation of blood, cerebral infarction, cerebral thrombosis, stroke, cerebral embolism, pulmonary embolism, ischemia and angina (including unstable angina). The compounds of the invention are also useful as inhibitors of blood coagulation in an ex vivo situation such as, for example, the storage of whole blood or other biological samples suspected to contain Factor Xa and in which coagulation is detrimental.

WO 98/21188 describes a range of Factor Xa inhibitors. Further particular examples of this type of compound including l-(5-chloroindol-2-ylsulphonyl)-4-[4-(6-oxo-lH- pyridazin-3-yl) benzoyl]piperazine are described in WO 99/57113. The applicants have found however, that by further derivatising the compounds of this type, enhanced properties may be obtained.

The present invention provides a compound of formula (I)

(0 ^•

wherein R¹ is hydrogen, C_1-3alkyl, R⁵R⁶aminoCi-₅alkyl, where R⁵ and R⁶ are each independently selected from hydrogen and C^alkyl, or

R⁵ and R⁶ may, together with the nitrogen to which they are attached, form a five- or six- membered heterocyclic ring, where said heterocyclic ring has 0 or 1 additional heteroatom;

n is 1 or 2; each R² are independently selected from hydrogen, oxo and C_1-3alkyl,

R³ is an indolyl, and

R⁴ a hydrogen or a halogen; or a pharmaceutically acceptable salt thereof.

In this specification the term "alkyl" includes both straight and branched chain alkyl groups but references to individual alkyl groups such as "propyl" are specific for the straight chain version only. An analogous convention applies to other generic terms.

It is to be understood that certain of the compounds of the formula (I) defined above can exist in solvated as well as unsolvated forms such as, for example, hydrated forms. It is to be understood that the invention encompasses all such solvated forms, which possess Factor Xa inhibitory activity.

It is further to be understood that, insofar as certain of the compounds of the formula (I) defined above may exist in optically active or racemic forms by virtue of one or more asymmetric carbon atoms, the invention encompasses any such optically active or racemic form which possesses Factor Xa inhibitory activity. The synthesis of optically active forms may be carried out by standard techniques of organic chemistry well known in the art, for example by synthesis from optically active starting materials or by resolution of a racemic form.

Further, "tautomer" or "tautomerism" refers to the coexistence of two (or more) compounds that differ from each other only in the position of one (or more) mobile atoms and in electron distribution, i.e. different tautomeric forms. An example may be keto-enol tautomers. Moreover, it is also to be understood that, insofar as certain of the compounds of the formula (I) defined above may exist in various tautomeric forms, the invention encompasses any such tautomeric forms which possesses Factor Xa inhibitory activity.

Compounds of the invention are potent inhibitors of Factor Xa, and may have improved selectivity over oxido squalene cyclase, better solubility and/or less cytochrome P 450 (CYP₄₅o) inhibition and/or Caco2-permeability than some related compounds. Caco2 is a cell line which mimics transport over the gut wall.

Suitable values in the compound of formula (I): for halogen: fluoro, chloro, bromo, iodo; for C_1-3alkyl: methyl, ethyl, propyl, isopropyl; for C_1-4alkyl: methyl, ethyl, propyl, isopropyl, n-butyl, secbutyl, isobutyl, tertbutyl; for C_1-5alkyl: C_1-4alkyl (as above), C_halky! (as above), n- butyl, isobutyl, pentyl, 2-pentyl, 3-pentyl, 2- methyl-1 -butyl, isopentyl, neopentyl, 3- methyl-2-butyI, 2-methyl-2-butyl.

In an embodiment of the invention a compound of formula (I) is disclosed wherein R¹ is hydrogen.

A further embodiment of the invention discloses a compound of formula (I) wherein R¹ is C_1-3alkyl, e.g. propyl, ethyl or methyl.

In a further embodiment of the invention a compound of formula (I) is disclosed wherein R¹ is R⁵R⁶aminoC₁.₃alkyl, where R⁵ and R⁶ are each independently selected from hydrogen and Ci_-3alkyl, e.g. propyl, ethyl or methyl, or R⁵ and R⁶ may, together with the nitrogen to which they are attached, form a six-membered heterocyclic ring, where said heterocyclic ring has 1 additional hetero oxygen. A further embodiment of the invention discloses a compound of formula (I) wherein one of

R is oxo.

In still a further embodiment of the invention a compound of formula (I) is disclosed wherein one of R² is C_1-3alkyl.

A further embodiment of the invention discloses a compound of formula (I) wherein R³ is 2-indolyl or 6-indolyl.

In a further embodiment of the invention a compound of formula (I) is disclosed wherein R⁴is chloro.

A further embodiment of the invention discloses a compound of formula (I) which is 6-{4-[S)-4-(3-chloro-lH-indole-6-sulfonyl)-2-methyl-6-sulfonyl)

-2-methyl-6-oxo-piperazin-l-ylmethyl]-phenyl}-2-methyl-2H-pyridazin-3-one,

6-{4-[(S)-4-(5-Chloro-lH-indole-2-sulfonyl)-3-methyl-2-oxo-piperazin-l-ylmethyl]- phenyl}-2-methyl-2H-pyridazin-3-one,

6-{4-[(S)-4-(5-Chloro-lH-indole-2-sulfonyl)-2-methyl-6-oxo-piperazin-l-ylmethyl]- phenyl } -2-methyl-2H-pyridazin-3 -one ,

6-{4-[4-(5-Chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2-(2- morpholin-4-yl-ethyl)-2H-pyridazin-3-one,

6-[4-({4-[(5-Chloro-lH-indol-2-yl)sulfonyl]-2-oxopiperazin-l-yl}methyl)ρhenyl]-2-[2-

(methylamino)ethyl]pyridazin-3 (2H)-one hydrochloride, 6- { 4- [4-(5-Chloro-lH-indole-2-sulf onyl)-2-oxo-piperazin- 1 -ylmethyl] -phenyl } -2-(2- dimethylamino-ethyl)-2H-pyridazin-3-one,

2-(2-Amino-ethyl)-6-{4-[4-(5-chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]- phenyl}-2H-pyridazin-3-one or

6-{4-[4-(5-Chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2H- pyridazin-3-one. A heterocyclic derivative of formula I, or pharmaceutically acceptable salt thereof, may be prepared by any process known to be applicable to the preparation of related compounds, such as those described in WO 98/21188 and WO 99/57113. Such procedures are provided as a further feature of the invention and are illustrated by the following representative processes in which, unless otherwise stated any functional group, for example amino, aminoalkyl, carboxy, indolyl or hydroxy, is optionally protected by a protecting group which may be removed when necessary.

Necessary starting materials may be obtained by standard procedures of organic chemistry and by reference to the processes used in the Examples.

For instance, the present invention provides a process for preparing a compound of formula (T) or a pharmaceutically acceptable salt thereof, which comprises the intramolecular reaction of an amino acid of formula (II), wherein the possible positioning of (R²)_n-1 corresponds to the possible positions of the corresponding (R²)_n-i in the - compound of formula (I), or a salt thereof, in the presence of a suitable base and a acid activating agent such as a carbodiimide.

Alternatively, a compound of formula (I) may be prepared by reaction of a compound of the formula (IH),

(111) wherein Z' is a displaceable group such as halo or sulfonate, with a compound of formula (IV),

(IV) wherein R¹ is as defined in relation to formula (I) and A is an activating group. Suitable activating groups A include metalised derivatives, such as with zinc or tin, and borane derivatives. The compound of formula (IV) is reacted with a compound of the formula (IH) to effect cross coupling where Z is triflate or a halo group, such as iodo, bromo or chloro. Suitably the reaction is catalysed by use of a transition state metal catalyst, such as palladium, for example Pd(PPh₃)₄.

Alternatively, a compound of formula (V),

(V) may be prepared by reaction of a compound of the formula (VI),

(Vl)

X may be a halogen which is conveniently hydrolysed under mildly acidic conditions at - 50 °C - 200 ⁰C, or an alkoxy group which may be dealkylated using standard conditions found in the literature to give compounds of formula (V). Alternatively, compounds of formula (I) are prepared by reaction a sulfonyl chloride derivative of formula (VII),

Cl- SO^-R-R⁴

(VII) with an amine of formula (VET) or a salt thereof,

(VIII) wherein the R-groups and n are as defined above in relation to formula (I).

This reaction is carried out using a base such as iV,iV-dimethyl aminopyridine, diisopropylethyl amine in inert solvents, typically dichloromethane and N,N- dimethylformamide at a temperature in the range -50 ⁰C - IOO ⁰C, conveniently at or near ambient temperature.

When an optically active form of a compound of the formula (I) is required, it may be obtained, for example, by carrying out one of the aforesaid procedures using an optically active starting material or by resolution of a racemic form of said compound using a conventional procedure, for example by the formation of diastereomeric salts, use of chromatographic techniques, conversion using stereospecific enzymatic processes, or by addition of temporary extra chiral group to aid separation.

The invention also relates to a process for preparing a compound of formula (I) which process comprises either

(a) intramolecularly reacting an amino acid of formula (II) or a salt thereof,

in the presence of a suitable base and a acid activating agent such as an carbodiimide; (b) reacting a compound of the formula (IH),

(III) wherein Z' is a displaceable group such as halo or sulfonate, with a compound of formula (IV),

(IV)

wherein A is an activating group;

(c) reacting a compound of the formula (VI),

(Vl) when X is a halogen, by hydrolysing or, when X is an alkoxy group, by dealkylating; or

(d) reacting a sulfonyl chloride derivative of formula (VII),

Cl- SOj-R-R⁴

(VlI) with an amine of formula (VIII),

(VIII) or a salt thereof.

As stated previously, the compounds of the formula (I) are inhibitors of the enzyme

Factor Xa. The effects of this inhibition may be demonstrated using one or more of the standard procedures set out hereinafter: -

a) Measurement of Factor Xa Inhibition

The FXa inhibitor potency was measured with a chromogenic substrate method, in a Plato 3300 robotic microplate processor (Rosys AG, CH-8634 Hombrechtikon, Switzerland), using 96-well, half-volume microtiter plates (Costar, Cambridge, MA, USA; Cat No 3690). Stock solutions of test substance in DMSO (72 μL), 10 mmol/L, alternatively 1 mmol/L were diluted serially 1:3 (24 + 48 μL) with DMSO to obtain ten different concentrations, which were analyzed as samples in the assay, together with controls and blanks. As control sample melagatran was analysed. The dilutions of each test substance were analyzed consecutively, row -wise on the microtiter plate, with wash-cycles between substances to avoid cross-contamination. First 2 μL of test sample or DMSO for the blank were added, followed by 124 μL of assay buffer (0.05 mol/L Tris-hydrochloric acid pH 7.4 at 37 ⁰C, 5 mM CaCl₂, ionic strength 0.15 adjusted with NaCl, 0.1 % bovine serum albumin, ICN Biomedicals, Inc, USA, lg/L) and 12 μL of chromogenic substrate solution (S-2765, Chromogenix, Molndal, Sweden) and finally 12 μL of FXa solution (human FXa, Haematologic Technologies Inc., Essec Junction, Vermont, USA), in buffer, was added, and the samples were mixed. The final assay concentrations were: test substance 0.0068- 133, respectively 0.00068-13.3 μmol/L, S-2765 0.40 mmol/L (K_M = 0.25 mmol/L) and FXa 0.1 nmol/L. The linear absorbance increase at 405 nm during 40 min incubation at 37 °C was used for calculation of percent inhibition for the test samples, as compared to references without inhibitor and/ or enzyme. The ICso-value, corresponding to the inhibitor concentration, which caused 50 % inhibition of the FXa activity, was calculated by fitting the data to a three-parameter equation by Microsoft XLfit. b) Measurement of Thrombin Inhibition The thrombin inhibitor potency was measured with a chromogenic substrate method developed in-house in principle as described in a) for FXa but using instead 0.3 mM of the chromogenic substrate solution S-2366 (Chromogenix., Molndal, Sweden) and 0.1 nmol/L human thrombin (Haematologic Technologies Inc., Essec Junction, Vermont, USA). c) Measurement of Anticoagulant Activity An in vitro assay whereby human blood is collected and added directly to a sodium citrate solution (3.2 g/100 mL, 9 parts blood to 1 part citrate solution). Plasma is prepared by centrifugation (1000 g, 15 minutes) and stored at -80 ⁰C.) and an aliquot was rapidly thawed at 37 °C on the day of the experiment and kept on ice before addition to the coagulometer cups. Conventional prothrombin time (PT) tests are carried out in the presence of various concentrations of a test compound and the concentration of test compound required to double the clotting time is determined. Thromborel ® S (Dade Behring, Liederbach, Germany) was reconstituted with 10 mL water. This solution was kept at 4 ⁰C and was used within one week. Before the experiment the solution was kept at 37 ⁰C for at least 30 minutes before start of the experiment. A ball coagulation timer KC 1OA from Heinrich Amelung GmbH. (Lemgo, Germany) was used to study if the compounds could prevent coagulation in human plasma. The time for 50 μl plasma with compound to coagulate after addition of 100 μl Thromborel S, the Prothrombin Time or PTj, is compared with the time it takes for pure plasma to coagulate, PT₀. With this technique the change in viscosity in the stirred solution is used to define clotting. The IC₅₀ is calculated from the curve of PTj/PT_o versus the inhibitor concentration in plasma, id est three times the final assay concentration. d) An in vivo Measurement of Antithrombotic Activity

The abdoman is opened and the caval vein exposed. The thrombotic stimulus is partial stasis to the caval vein and a piece of filter paper soaked with ferric chloride and superimposed to the external surface of the vein. Thrombus size is determined as the thrombus wet weight at the end of the experiment. (Ref Thromb. Res. 2002;107:163-168). When tested In the above mentioned screen a) Measurement of Factor Xa Inhibition, the compounds of the Examples gave IC₅₀ values for inhibition of Factor Xa activity of less than 10 μM, indicating that the compounds of the invention are expected to possess useful therapeutic properties.

Specimen results are shown in the following Table:

A feature of the invention is a compound of formula (I), or a pharmaceutically acceptable salt thereof, for use in medical therapy.

According to a further feature of the invention there is provided a pharmaceutical composition which comprises a compound of formula (I), or a pharmaceutically acceptable salt thereof, in association with a pharmaceutically acceptable diluent or carrier. The composition may be in a form suitable for oral use, for example a tablet, capsule, aqueous or oily solution, suspension or emulsion; for topical use, for example a cream, ointment, gel or aqueous or oily solution or suspension; for nasal use, for example a snuff, nasal spray or nasal drops; for vaginal or rectal use, for example a suppository; for administration by inhalation, for example as a finely divided powder such as a dry powder, a microcrystalline form or a liquid aerosol; for sub-lingual or buccal use, for example a tablet or capsule; or for parenteral use (including intravenous, subcutaneous, intramuscular, intravascular or infusion), for example a sterile aqueous or oily solution or suspension. In general the above compositions may be prepared in a conventional manner using conventional excipients. The amount of active ingredient (that is a compound of the formula (I), or a pharmaceutically-acceptable salt thereof) that is combined with one or more excipients to produce a single dosage form will necessarily vary depending upon the host treated and the particular route of administration. For example, a formulation intended for oral administration to humans will generally contain, for example, from 0.5 mg to 2 g of active agent compounded with an appropriate and convenient amount of excipients which may vary from about 5 to about 98 percent by weight of the total composition. Dosage unit forms will generally contain about 1 mg to about 500 mg of an active ingredient.

According to a further feature of the invention there is provided a compound of formula (I), or a pharmaceutically-acceptable salt thereof, for use in a method of treatment of the human or animal body by therapy.

The invention also includes the use of such an active ingredient (i.e. a compound of the formula (I), or a pharmaceutically-acceptable salt thereof) in the production of a medicament for use in:-

(i) producing a Factor Xa inhibitory effect; (ii) producing an anticoagulant effect;

(iii) producing an antithrombotic effect;

(iv) treating a Factor Xa mediated disease or medical condition; (v) treating a thrombosis mediated disease or medical condition; (vi) treating coagulation disorders; and/or (vii) treating thrombosis or embolism involving Factor Xa mediated coagulation.

The invention also includes a method of producing an effect as defined hereinbefore or treating a disease or disorder as defined hereinbefore which comprises administering to a warm-blooded animal requiring such treatment an effective amount of an active ingredient as defined hereinbefore.

The size of the dose for therapeutic or prophylactic purposes of a compound of the formula (I) will naturally vary according to the nature and severity of the medical condition, the age and sex of the animal or patient being treated and the route of administration, according to well known principles of medicine. As mentioned above, compounds of the formula (I) are useful in the treatment or prevention of a variety of medical disorders where anticoagulant therapy is indicated. In using a compound of the formula (I) for such a purpose, it will generally be administered so that a daily oral dose in the range, for example, 0.5 to 100 mg/kg body weight/day is received, given if required in divided doses. In general lower doses will be administered when a parenteral route is employed, for example a dose for intravenous administration in the range, for example, 0.01 to 10 mg/kg body weight/day will generally be used. For preferred and especially preferred compounds of the invention, in general, lower doses will be employed, for example a daily dose in the range, for example, 0.1 to 10 mg/kg body weight/day. In general a preferred dose range for either oral or parenteral administration would be 0.01 to 10 mg/kg body weight/day.

Although the compounds of formula (I) are primarily of value as therapeutic or prophylactic agents for use in warm-blooded animals including man, they are also useful whenever it is required to produce an anticoagulant, effect, for example during the ex vivo storage of whole blood or in the development of biological tests for compounds having anticoagulant properties.

The compounds of the invention may be administered as a sole therapy or they may be administered in conjunction with other pharmacologically active agents such as a thrombolytic agent, for example tissue plasminogen activator or derivatives thereof or streptokinase. The compounds of the invention may also be administered with, for example, a known platelet aggregation inhibitor (for example aspirin, a thromboxane antagonist or a thromboxane synthase inhibitor), a known hypolipidaemic agent or a known anti-hypertensive agent.

The compounds of the invention may also be combined and/or co-administered with any antithrombotic agent(s) with a different mechanism of action, such as one or more of the following: the anticoagulants unfractionated heparin, low molecular weight heparin, other heparin derivatives, synthetic heparin derivatives (e.g. fondaparinux), vitamin K antagonists, synthetic or biotechnological inhibitors of other coagulation factors than FXa (e.g. synthetic thrombin, FVIIa, FXIa and FIXa inhibitors, and rNAPc2), the antiplatelet agents acetyls alicylic acid, ticlopidine and clopidogrel; thromboxane receptor and/or synthetase inhibitors; fibrinogen receptor antagonists; prostacyclin mimetics; phosphodiesterase inhibitors; ADP-receptor (P2X1 , P2Y1 , P2Y12 [P2T]) antagonists; and inhibitors of carboxypeptidase U (CPU or TAFIa) and inhibitors of plasminogen activator inhibitor-1 (PAI-I).

The compounds of the invention may further be combined and/or co-administered with thrombolytics such as one or more of tissue plasminogen activator (natural, recombinant or modified), streptokinase, urokinase, prourokinase, anisoylated plasminogen-streptokinase activator complex (APSAC), animal salivary gland plasminogen activators, and the like,. in the treatment of thrombotic diseases, in particular myocardial infarction.

The invention further relates to a combination comprising a compound of formula (I) and any antithrombotic agent(s) with a different mechanism of action. Said antithrombotic agent(s) may be, for example, one or more of the following: the anticoagulants unfractionated heparin, low molecular weight heparin, other heparin derivatives, synthetic heparin derivatives (e.g. fondaparinux), vitamin K antagonists, synthetic or biotechnological inhibitors of other coagulation factors than FXa (e.g. synthetic thrombin, FVIIa, FXIa and FIXa inhibitors, and rNAPc2), the antiplatelet agents acetylsalicylic acid, ticlopidine and clopidogrel; thromboxane receptor and/or synthetase inhibitors; fibrinogen receptor antagonists; prostacyclin mimetics; phosphodiesterase inhibitors; ADP-receptor (P2X1, P2Y1, P2Y12 [P2T]) antagonists; and inhibitors of carboxypeptidase U (CPU or TAFIa) and inhibitors of plasminogen activator inhibitor- 1 (PAI-I).

Moreover, the invention further relates to a combination comprising a compound of formula (I) and thrombolytics, e.g. one or more of tissue plasminogen activator (natural, recombinant or modified), streptokinase, urokinase, prourokinase, anisoylated plasminogen-streptokinase activator complex (APSAC), animal salivary gland plasminogen activators.

Further, the invention also relates to a combination comprising a compound of formula (I) and thrombolytics, e.g. one or more of tissue plasminogen activator (natural, recombinant or modified), streptokinase, urokinase, prourokinase, anisoylated plasminogen- streptokinase activator complex (APSAC), animal salivary gland plasminogen activators, and the like, in the treatment of thrombotic diseases, in particular myocardial infarction.

The invention will now be illustrated in the following Examples in which, unless otherwise stated:-

(i) Yields are given for illustration only and are not necessarily the maximum attainable. Single node microwave irradiation was performed using either an Emrys Optimizer or a Smith Creator from Personal Chemistry. All solvents and reagents were used as purchased without purification unless noted.;

(ii) The end-products have satisfactory high resolution mass spectral (HRMS) data as analysed on aMicromass QTof Micro spectrometer equipped with an Agilent 1100 LC system high performance liquid chromatography (HPLC). The spectrometer was continually calibrated with leucine enkephaline C_2SH₃₇N₅O₇ (m/z 556.2771) . MS conditions: Electrospray ionization, positive mode, capillary voltage 2.3 kV and desolvation temperature 150 °C. Accurate mass was determined for positive ionization using leucine enkephaline (m/z 556.2771) as lock mass. Structures were confirmed by ¹H nuclear magnetic resonance (¹H NMR) spectra which were obtained with either a Varian Unity plus or a Varian Inova spectrometer operating at 400, 500 and 600 MHz respectively. Chemical shift values were measured on the delta scale; the following abbreviations have been used: s, singlet; d, doublet; t, triplet; q, quartet; sept, septet; m, multiplet; (iii) Intermediates were generally characterised as the end products with the exception of HRMS data.;

(iv) Preparative reversed phase HPLC was performed using a Waters Prep LC 2000 with UV detection equipped with a 25 cm x 2 cm or 30 x 5 cm C8 or C18 columns from Kromasil. Preparative chiral resolution using HPLC was performed using a Gilson 306 with UV detection equipped with either a Ciralpak AS (25 x 2 cm) (ester separations), a Chiralpak AD (25 x 2 cm) (amide separations) or a Chirobiotic R (25 x 2 cm) (carboxylic acid separation) column using 100 % methanol or methanol / acetic acid / triethyl amine 100 / 0.1 / 0.05. All chiral separations were performed at 40 ⁰C.

Example 1

β^Φ^^-CS-chloro-lH-indole-β-sulfonyO-l-methyl-ό-sulfony^-l-methyl-ό-oxo- piperazin-l-yImethyl]-phenyl}-2-methyl-2H-pyrϊdazin-3-one

A) ((S)-2-Amino-propyl)-carbamic acid tert-butyl ester

To a solution of trietylamine (0.95 mL, 6.8 mmol) in 15 mL ethanol was added (s)-(-)- diaminopropane (252 mg, 74.1 mmol). The reaction mixture was stirred under reflux over night. Solvent was evaporated. Water was added and the pH was adjusted to pH 3 by addition of 2 M hydrochloric acid followed by extraction with dichloromethane. The aqueous phase was made alkaline by addition of 2 M sodium hydroxide and extracted with dichloromethane. The organic phase was dried over magnesium sulfate and dried in vacuo over night to give the the sub-title compound (211 mg, 36 % yield) and the by-product ((S)-2-amino-l-methyl-ethyl)-carbarnic acid tert-butyl ester in a 3 : 1 mixture according to NMR.

¹H NMR (400 MHz; chloroform-d as solvent and internal reference) δ(ppm) 1.09 (d, 3H, J = 6.5 Hz), 1.45 (s, 9H), 2.91 (m, IH), 3.04 (m, IH), 3.16 (m, IH)

B) 4-(^*l -Methyl-6-oxo-l ,6-dihydro-pyridazin-3-yl)benzaldehyde To a solution mixture containing 1,2-dimethoxyethane : ethanol : water 7 : 3 : 2 (5 mL) was added-formylboronic acid (250 mg, 1.67 mmol), 6-chloro-2-methyl-2H-pyridazin-3- one (421 mg, 1.67 mmol), caesium carbonate (543 mg, 1.67 mg) and benzylbis(triphenyl- phosphine)palladium(II)chloride 101 mg, 0.133 mmol). The reaction mixture is heated in a micro wave oven at 150⁰C for 10 minutes. The mixture was filtered and concentrated. Purification by flash chromatography with a gradient from heptane / ethyl acetate (1 : 1) to ethyl acetate / triethylamine (5 %) gave 946 mg of the sub-title compound (88 % yield).

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ(ppm) 3.89 (s, 3H), ^' 8.01 (m, 2H), 8.09 (m, 4H), 10.04 (s, IH) C) { (S)-2-[4-(l -Methyl-6-oxo-l ,6-dihvdro-pyridazin-3-yl)-benzylamino1-propyl } - carbamic acid tert-butyl ester

To a solution of 4-(l-methyl-6-oxo-l,6-dihydro-ρyridazin-3-yl)benzaldehyde (300 mg, 1.40 mmol) from step B in dry dichloromethane was added ((S)-2-amino-propyl)carbamic acid tert-butyl ester (211 mg, 1.21 mmol) from step A. Acetic acid (160 μL, 2.80 mmol) was added dropwise under stirring followed by addition of sodium triacetoxyborohydride (712 mg, 3.36 mmol) and stirring over night at room temperature. Purification by preparative HPLC gave a mixture of products with the sub-title compound (120 mg, 23 %) being the major product. The material was used directly in the next step.

D) (fSV2-((2-Chloro-acetyl) -r4-(l-methyl-6-oxo-l,6- dihvdro-pyridazin-3-yl)- benzylaminol -propyl} -carbamic acid tert-butyl ester

A solution of {(S)-2-[4-(l-methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)-benzylamino]- propyl} -carbamic acid tert-butyl ester (120 mg, 0.322 mmol) from step C in dichloromethane is cooled in an ice bath and triethylamine (80 μL, 0.55 mmol) was added. Bromoacetyl chloride (76 mg, 0.48 mmol) in dichloromethane was added and the mixture was stirred at room temperature for 2 hours. The solvent was evaporated in vacuo and the crude was purified by preparative HPLC to give a mixture of products with the sub-title compound being the major product (130 mg, 81 % yield) which was used further in the next step.

E) N-((S V2- Amino- 1 -methyl-ethyl)-2-chloro-N- F4-( 1 -methyl-6-oxo- 1 ,6-dihvdro- Pyridazin-3-yl)-benzvn-acetamide

A solution of ((S)-2-{ (2-chloro-acetyl)-[4-(l-methyl-6-oxo-l ,6-dihydro-pyridazin-3-yl)- benzylamino]-propyl } -carbamic acid tert-butyl ester (217 mg, 0.44 mmol) from step D in methanol (5 mL) was cooled on an ice bath and methanol saturated with hydrochloric acid (3 mL) is added dropwise. The reaction mixture was stirred at room temperature for 1 hour and then concentrated and dried in vacuo. The crude sub-title product was used without further purification.

F) 2-Methyl-6-r4-(S)-2-methyl-6-oxo-piperazin-l-ylmethyl)-phenvn-2H-pyridazin-3-one

A solution of N-((S)-2-amino-l-methyl-ethyl)-2-chloro-N-[4-(l-methyl-6-oxo-l,6-dihydro- pyridazin-3-yl)-benzyl]-acetamide (173 mg, 0.44 mmol) from step E in ΛζiV-dimethyl- formamide (4 mL) is cooled in an ice bath and triethylamine ( 150 μ.L, 1.08 mmol ) is added dropwise. The reaction mixture is stirred at room temperature for 48 hours. Methylene chloride and water was added at 0 ⁰C. The organic layer was separated, dried over magnesium sulfate, filtered, concentrated and dried in vacuo. Purification by flash chromatography, toluene / ethyl acetate (1 : 1) gave pure sub-title product (136 mg, 99 %).

¹H NMR (400 MHz, chloroform-d as solvent and internal reference) δ(ppm) 1.38 (d, 3H), 2.82 (dd, 2H), 3.07 (dd, 2H), 3.18 (m, IH), 3.45 (m, IH), 3.83 (s, 3H) 4.38 (d, 2H), 5.12 (d, 2H), 7.04 (d, IH), 7.40 (d, IH), 7.83 (d, 2H), 8.02 (d, IH)

G) 6-(4-rS)-4-(l-Benzenesulfonyl-3-chloro-lH-indole-6-sulfonyl)-2-methyl-6-sulfonyl)-2- methyl-6-oxo-piperazin-l-ylmethyl1-phenyll-2-methyl-2H-pyridazin-3-one

2-Methyl-6-[4-(S)-2-methyl-6-oxo-piperazin-l-ylmethyl)-phenyl]-2H-pyridazin-3-one (70 mg, 0.22 mmol) from step F was dissolved in dichloromethane and cooled to 0 ⁰C.

Triethylamine (23 mg, 0.22 mmol) and l-benzenesulfonyl-3-chloro~lH-indαle-6-sulfonyl chloride (105 mg, 0.27 mmol) dissolved in dichloromethane was added. The reaction was stirred at room temperature for 4 hours. Dichloromethane and water was added. The organic phase was washed with water, brine, dried over magnesium sulfate and evaporated. The crude was purified by preparative HPLC to give the sub-title product as a white powder after evaporation and freeze drying ( 60 mg, 40 % yield).

¹HNMR (400 MHz, chloroform-d as solvent and internal reference) δ(pρm) 1.38 (d, 3H, / = 6.3 Hz), 2.77 (m, IH), 3.40 (d, IH, J = 16.5 Hz), 3.49 (m, 2H), 4.0 (d, IH, J= 15.0 Hz), 4.11 (d, IH, J = 16.5 Hz), 5.27 (d, IH, /= 15 Hz), 5.30 (s, 3H), 7.01 (d, IH, J= 9.6 Hz), 7.25 (d, 2H, J = 8.1), 7.50 - 7.54 (m, 2H), 7.54 - 7.64 (m, 2H), 7.67 - 7.74 (m, 4H), 7.78 (s, IH), 7.91 - 7.94 (m, 2H), 8.44 (s, IH)

m

To 6- { 4- [S)-4-(l -benzenesulfonyI-3-chloro- lH-indole-6-sulfonyl)-2-methyl-6-sulf onyl)-2- methyl-6-oxo-piperazin-l-ylmethyl]-phenyl}-2-methyl-2H-ρyridazin-3-one (60 mg, 0.090 mmol) from step G in tetrahydrofuran was added tetrabutylammonium fluoride (28 mg, 0.090 mmol, 1 M in tetxahydrofuran). The mixture was heated in a microwave oven ( 5 minutes, 100⁰C ). Dichloromethane and water was added. The organic phase was washed with water, brine, dried over magnesium sulfate and evaporated. The crude was purified by preparative HPLC to give the title product (35 mg, 74 %).

¹H NMR (400 MHz, chloroform-d as solvent and internal reference) δ(ppm) 1.38 (d, 3H, J = 6.1 Hz), 2.8 (m, IH), 3.49 (m, 3H), 3.85 (s, 3H), 4.02 (d, IH, J = 15.0 Hz), 4.11 (d, IH, J = 16.0 Hz), 5.24 (d, IH, /= 15.0 Hz), 6.99 (d, IH, J= 9.7 Hz), 7.22 (d, 2H, J= 8.3), 7.39 (d, IH, J - 2.6 Hz), 7.50 (dd, IH, J = 1.5, 8.5 Hz), 7.62 (d, IH, H = 9.7), 7.67 (d, 2H, J = 8.3 Hz), 7.75 (d, IH, / = 8.5), 7.94 (d, IH, J = 1.0 Hz), 9.69 (s, 1 H).

HRMS (ESI+) calc. [M+H]⁺ 526.1310, found 526.1322.

Example 2

6-{4-[(S)-4-(5-Chloro-lH-indole-2-suIfonyl)-3-methyl-2-oxo-piperazin-l-ylmethyl]- phenyl}-2-methyl-2H-pyridazin-3-one

A) { 2- [4-( l-Methyl-6-oxo- 1 ,6-dihvdro-pyridazin-3-yl)-b&nzylamino1 -ethyl 1 -carbamic acid tert-butyl ester

A solution of 4-(l,6-dihydro-l-methyl-6-oxo-3-pyridazinyl)benzaldehyde (0.50 g, 2.33 mmol, prepared according to Jpn. Kokai Tokyo Koho 1980 JP55152748) and N-(I- aminoethyl)carbamic acid tert-butyl ester (0.374 g, 2.33 mmol) in anhydrous dichloromethane (20 mL) at room temperature was treated with sodium triacetoxy- borohydride (1.48 g, 7.00 mmol). The slurry was stirred at room temperature under nitrogen atmosphere for 3 hours. The reaction mixture was cooled to 0⁰C and quenched with water (50 mL). Dichloromethane was evaporated and water was removed by freeze- drying. The solid crude was dissolved in dichloromethane and filtered. The crude dichloromethane solution was evaporated and the residue was purified by preparative reversed phase HPLC using a gradient of acetonitrile / 5 % acetonitrile- water phase containing 0.1 M ammonium acetate to give the sub-title compound (0.48 g, 57 %).

¹HNMR (400 MHz, dimethyl sulfoxide-dg as solvent and internal reference) δ(ppm) 8.02 (d, IH, / = 9.8 Hz), 7.80 (broad d, 2H, J = 8.3 Hz), 7.41 (broad d, 2H, J = 8.3 Hz), 7.01 (d, IH, /= 9.8 Hz), 6.71 (t, IH, J= 5.3 Hz), 3.71 (s,3H), 3.70 (s, 2H), 3.00 (q,2H, J= 6.3 Hz), 2.51 (m, 2H), 1.34 (s, 9H).

B) 2-Methyl-6-r4-((S)-3-methyl-2-oxo-piperazin-l-ylmethyI)-phenyn-2H-pyridazin-3-one

{2-[4-(l-Methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)-benzylamino]-ethyl}-carbamic acid tert-butyl ester (335 mg, 0.93 mmol) from step A was dissolved in anhydrous dichloromethane (4 mL) and cooled to 0 ⁰C. Triethylamine (227 mg, 2.24 mmol) was added and a solution of (R)-2-chloro-propionyl chloride (142 mg, 1.12 mmol) in anhydrous dichloromethane (1 mL) was added dropwise during 6 minutes. The reaction was stirred for 5 minutes at 0 °C and 2 hours at room temperature. Dichloromethane and water was added and the two-phase system was stirred for 5 minutes and the layers were separated. The aqueous layer was extracted with dichloromethane and the combined organic layers were washed with brine. The brine layer was extracted with dichloromethane and the combined organic layers were dried, filtered and concentrated. The residue was cooled by an ice-bath, a solution of 1.25 M hydrochloric acid in methanol was added and the reaction was stirred overnight at room temperature. The methanol was removed in vacuo and the residue was suspended in anhydrous iV,N-dimethylformamide and cooled to 0 ⁰C. Triethyl amine was added and the reaction was stirred at room temperature for 1 hour 20 minutes. Water (0.5 mL) was added and the solution was purified by preparative HPLC using a gradient of acetonitrile 15 % acetonitrile-water phase containing 0.1 M ammonium acetate followed by flash chromatography using a gradient of methanol in dichloromethane containing 5 % triethylamine, to give the sub-title compound (176 mg, 56 % yield).

¹H NMR (500 MHz; methanol-^ as solvent and internal reference) δ(ppm) 7.99 (d, IH, J = 9.7 Hz), 7.86 (broad d, 2H, / = 8.4 Hz), 7.39 (broad d, 2H, J = 8.4 Hz), 7.05 (d, IH, J = 9.7 Hz), 4.67 (ABd, IH, J= 14.9 Hz), 4.60 (ABd, IH, /= 14.9 Hz)₇ 3.85 (s, 3H), 3.54 (q, IH, /= 7.0 Hz), 3.38 - 3.46 (m, IH), 3.25 (dt, IH, /= 12.0, 8.1 Hz), 3.14 (m, IH), 2.93 - 3.00 (m, IH), 1.39 (d, 3H, J= 7.0 Hz)

C) 6-j4-r(S)-4-(l-BenzenesuIfonyl-5-chloro-lH-indole-2-sulfonyl)-3-methyl-2-oxo- piρerazin-l-ylmethyn-phenyl)-2-methyl-2H-pyridazin-3-one A solution of l-benzenesulfonyl-5-chloro-lH-indole-2-sulfonylchloride (503 mg, 1.29 mmol) in anhydrous dichloromethane (3 mL) was added dropwise to a solution of 2- methyl-6-[4-((S)-3-methyl-2-oxo-piperazin-l-ylmethyl)-phenyl]-2H-pyridazin-3-one (155 mg, 0.50 mmol) from step B and triethylamine (311 mg, 3.07 mmol) in anhydrous dichloromethane (5 mL) at 0 °C and the reaction was stirred for 2 hours at room temperature. More l-benzenesulfonyl-S-chloro-lH-indole-^-sulfonylchloride (194 mg, 0.50 mmol) and triethylamine (50 mg, 0.50 mmol) was added and the reaction was stirred overnight at room temperature. Aqueous saturated sodium hydrogen carbonate and dichloromethane was added, the two-phase system was stirred for 10 minutes and the layers were separated. The organic layer was washed with brine, filtered, dried over sodium sulfate, filtered and concentrated. The residue was purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile-water phase containing 0.1 M ammonium acetate to give the sub-title compound (40 mg, 12 % yield). ¹HNMR (500 MHz; chloroform-d as solvent and internal reference) δ(ρpm) 8.17 (d, IH, / = 9.1 Hz), S.02 (dd, 2H, J= 8.6, 1.1 Hz), 7.72 (d, 2H, J= 8.2 Hz), 7.66 (d, IH, J = 9.7 Hz), 7.54 - 7.60 (m, 2H), 7.50 (s, IH), 7.42 - 7.47 (m, 3H), 7.31 (d, 2H, J= 8.2 Hz), 7.03 (d, IH, J = 9.7 Hz), 4.60 - 4.71 (m, 3H), 4.01 - 4.10 (m, IH), 3.89 (s, 3H), 3.50 - 3.60 (m, 2H), 3.07 - 3.14 (m, IH), 1.54 (d, IH, J = 7.2 Hz)

m

6-{4-[(S)-4-(l-Benzenesulfonyl-5-chloro-lH-indole-2-sulfonyl)-3-methyl-2-oxo- piperazin-l-ylmethyl]-phenyl}-2-methyl-2H-ρyridazin-3-one (39 mg, 0.058 mmol) from step C was treated essentially as in example 3 step G to give the title compound (18 mg, 57 % yield).

¹H NMR (500 MHz; methanols / chloroform-d, 1 : 1 as solvent with methanol-d₄ as internal reference) δ(ppm) 7.73 (d, IH, J = 9.7 Hz), 7.57 (d, IH, / = 8.3 Hz) 7.29 - 7.35 (m, 3H), 7.19 (dd, IH, J = 8.8, 1.7 Hz), 7.04 (d, IH, J = 9.8 Hz), 6.93 (s, IH), 6.83 (d, 2H, J = 8.1 Hz), 4.89 (d, IH, J = 14.9 Hz), 4.62 (m, IH), 3.93 - 4.03 (m, 2H), 3.87 (s, 3H), 3.57 (ddd, IH, J= 15.0, 11.8, 3.9 Hz), 3.17 (dt, IH, J= 12.0, 4.6 Hz), 2.99 - 3.06 (m, IH), 1.57 (d, J = 7.1 Hz).

HRMS (ESI+) calc. [M+Hf 526.1310, found 526.128L

Example 3

6-{4-[(S)-4-(5-ChIoro-lH-indole-2-sulfonyl)-2-methyl-6-oxo-piperazin-l-yImethyl]- phenyl}-2-methyl-2H-pyridazin-3-one

A) ((S)-2-Amino-propyl)-carbamic acid tert-butyl

To a solution of triethylamine (0.95 mL, 6.8 mmol) in 15 mL ethanol was added (S)-(-)- diaminopropane (252 mg, 74.1 mmol). The reaction mixture was stirred under reflux over night. Solvent was evaporated. Water was added and the pH was adjusted to 3 by addition of 2 M hydrochloric acid followed by extraction with dichloromethane. The aqueous phase was made alkaline by addition of 2 M sodium hydroxide and extracted with dichloromethane. The organic phase was dried over magnesium sulfate and dried in vacuo over night to give the desired sub-title product (211 mg, 36 % yield) and the by-product 5 ((S)-2-amino-l-methyl-ethyl)-carbamic acid tert-butyl ester in a 3 : 1 mixture according to ¹H NMR.

¹H NMR (400 MHz; chloroform-d as solvent and internal reference) δ(ppm) 1.09 (d, 3H, J = 6.5 Hz), 1.45 (s, 9H), 2.91 (m, IH), 3.04 (m, IH), 3.16 (m, IH)

I₀

B) |(S)-2-r4-(l-Methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)-benzylamino1-propyl}- carbamic acid tert-butyl ester

To a solution of 4-(l-methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)benzaldehyde (300 mg, 1.40 mmol) from Example 1 step B in dry dichloromethane was added ((S)-2-arnino- I₅ propyl)carbamic acid tert-butyl ester (211 mg, 1.21 mmol). Acetic acid (160 μL, 2.80 mmol) was added dropwise under stirring followed by addition of sodium triacetoxyboro- hydride (712 mg, 3.36 mmol) and stirring overnight at room temperature. Purification by preparative HPLC gave a mixture of products with the sub-title compound (120 mg, 23 %) being the major product. The material was used directly in the next step.

20

C) ((S)-2-((2-Chloro-acetyl)-r4-(l-methyl-6-oxo-l,6-dihydro-pyridazin-3-ylV benzylaminoi-propyll-carbamic acid tert-butyl ester

A solution of {(S)-2-[4-(l-methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)-benzylamino]- propyl}-carbamic acid tert-butyl ester (120 mg, 0.322 mmol) from step B in dichloro- 25 methane is cooled in an ice bath and triethylamine (80 μL, 0.55 mmol) was added. Bromo- acetyl chloride (76 mg, 0.48 mmol) in dichloromethane was added and the mixture was stirred at room temperature for 2 hours. The solvent was evaporated in vacuo and the crude was purified by preparative HPLC to give a mixture of products with the sub-title compound being the major product (130 mg, 81 % yield) which was used further in the next step.

D) N-((S)-2-Amino-l-methvI-ethylV2-chloro-N-r4-(l-methyl-6-oxo-l,6-dihvdro- 5 pyridazin-3-ylVbenzyll-acetamide

A solution of ((S)-2-{(2-chloro-acetyl)-[4-(l-methyl-6-oxo-l,6-dihydro-pyridazin-3-yl)- benzylamino]-propyl}-carbamic acid tert-butyl ester (217 mg, 0.44 mmol) from step C in methanol (5 mL) was cooled on an ice bath and methanol saturated with hydrochloric acid (3 mL) is added dropwise. The reaction mixture was stirred at room temperature for 1 hour io and then concentrated and dried in vacuo. The crude sub-title product was used without further purification.

E) 2-Methyl-6-r4-(S)-2-methyl-6-oxo-piperazin-l-ylmethyl)-phenyll-2H-pyridazin-3-one

A solution of N-((S)-2-amino-l-methyl-ethyl)-2-chloro-iV-[4-(l-methyl-6-oxo-l,6-dihydro- I₅ pyridazin-3-yl)-benzyl]-acetamide (173 mg, 0.44 mmol) from step D in iV,N-dimethyl- formamide (4 mL) is cooled in an ice bath and triethylamine ( 150 μL, 1.08 mmol) is added dropwise. The reaction mixture is stirred at room temperature for 48 hours. Methylene chloride and water was added at 0 ⁰C. The organic layer was separated, dried over magnesium sulfate, filtered, concentrated and dried in vacuo. Purification by flash 20 chromatography, toluene / ethyl acetate (1 : 1) gave pure title product (136 mg, 99 %).

¹HNMR (400 MHz, chloroform-d as solvent and internal reference) δ(ppm) 1.38 (d, 3H), 2.82 (dd, 2H), 3.07 (dd, 2H), 3.18 (m, IH), 3.45 (m, IH), 3.83 (s, 3H) 4.38 (d, 2H), 5.12 (d, 2H), 7.04 (d, IH), 7.40 (d, IH), 7.83 (d, 2H), 8.02 (d, IH)

2S

F) 6-(4-r(S)-4-(l-Benzenesulfonyl-5-chloro-lH-indole-2-sulfonyI)-2-methyl-6-oxo- piperazin- 1 -ylmethyl^"! -phenyl } -2-methyl-2H-pyridazin-3-one

2-Methyl-6-[4-((S)-2-methyl-6-oxo-ρiperazin-l-ylmethyl)-ρhenyl]-2H-pyridazin-3-one (69 mg, 0.22 mmol) from step E was dissolved in 0.2 mL dichloromethane and cooled to 0 ⁰C. Triethylamine (45.3 mg, 0.448 mmol) and l-benzenesulfonyl-5-chloro~lH-indόle-2- sulfonyl chloride (89 mg, 0.23 mmol) dissolved in dichloromethane (0.5 mL) was added. The reaction was stirred 1.5 hours at room temperature. Dichloromethane and water was added. The organic phase was washed three times with water, once with brine, dried over 5 sodium sulfate and evaporated. The crude was further purified by preparative HPLC (C8- column) using a gradient of acetonitrile / 5 % acetonitrile water phase containing 0.1 M ammonium acetate to give the sub-title product as a light brown powder after evaporation and freeze drying (17 mg, 11 % yield).

o ¹H NMR (400 MHz, chloroform-d as solvent and internal reference) δ (ppm) 1.34 (d, 3H, J = 6.1 Hz), 3.54 (m, 2H), 3.77 (dd, IH, J = 3.3, 13.1 Hz), 3.87 (d, IH, J = 17.2 Hz), 3.88 (s, 3H), 4.08 (d, IH, / = 15.1 Hz), 4.25 (d, IH, / = 17.2 Hz), 5.32 (d, IH, J = 15.1 Hz), 7.03 (d, IH, / = 9.8 Hz), 7.33 (d, 2H, J = 8.3 Hz), 7.46 (m, 4H), 7.58 (m, 2H), 7.66 (d, IH, J = 9.8 Hz), 7.74 (d, 2H, J = 8.3 Hz), 8.01 (m, 2H), 8.23 (d, IH, J = 9.1 Hz). 5

G)

To 6-{4-[(S)-4-(l-benzenesulfonyl-5-chloro-lH-indole-2-sulfonyl)-2-methyl-6-oxo- piperazin-l-ylmethyl]-phenyl}-2-methyl-2H-pyridazin-3-one (17 mg, 0.026 mmol) from step F in 0.3 mL tetrahydrofuran was added tetrabutylammonium fluoride (0.040 mL, 1 M 0 in tetrahydrofuran). The mixture was heated in a microwave oven (5 minutes, 100 ⁰C).

Dichloromethane and water was added. The organic phase was separated and washed twice with water, once with brine, dried over sodium sulfate and evaporated. The crude was further purified by flash chromatography using ethyl acetate (100 %) as eluent to give 12 mg of the title compound as a white powder after evaporation of solvent (yield 89 %). S

¹H NMR (400 MHz, chloroform-das solvent and internal reference) δ(ppm) 1.38 (d, 3H, / = 6.1 Hz), 2.94 (m, IH), 3.52 (m, 2H), 3.69 (d, IH, J = 16.4 Hz), 3.86 (s, 3H), 4.04 (d, IH, J = 15.3 Hz), 4.24 (d, IH, / = 16.4 Hz), 5.29 (d, IH, / = 15.3 Hz), 6.98 (s, IH), 7.02 (d, IH, J = 9.5 Hz), 7.28 (m, 3H), 7.34 (d, IH, J = 8.8 Hz), 7.61 (d, IH, J = 9.5 Hz) 7.66 (m, 3H).

HRMS (ESI+) calc. [MH-H]⁺ 526.1310, found 526.1274.

Example 4

6-{4-[4-(5-ChIoro-lH-indole-2-suIfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2-(2- morpholin-4-yϊ-ethyl)-2H-pyridazin-3-one

A) 3-Oxo-piperazine-l-carboxylic acid tert-butyl ester Piperazinone (20 g, 0.20 mol) was dissolved in 120 mL iV,iV-dimethylformamide. Di-tert- butyldicarbonate (47.9g, 0.20 mmol) was added in portions. After 5 minutes the product precipitated. The solids formed were filtered and dried and used further in step B.

¹HNMR (400 MHz, chloroform-das solvent and internal reference) δ(ppm) 1.46 (s, 9H), 3.37 (m, 2H), 3.62 (t, 2H, J = 5.1 Hz), 4.08 (s, 2H).

B) 4-(4-Iodo-benzγlV3-oxo-piperazine-l-carboxylic acid tert-butyl ester

Sodium hydride (1.30 g, 33.5 mmol) was added to a slurry of 3-oxo-piperazine-l- carboxylic acid tert-butyl ester (6.70 g, 33.4 mmol) from step A in 25 mL dry N,N- dimethylformamide and 90 mL dry tetrahydrofuran under argon atmosphere and cooled to O⁰C. The mixture was stirred at room temperature until a solution was obtained after 30 minutes. 4-Iodobenzyl bromide (9.90 g, 33.4 mmol), dissolved in 20 mL tetrahydrofuran, was added dropwise. The reaction was stirred for 1 hour to give a white slurry. Ethyl acetate and water was added. The organic phase was washed three times with water, once with brine, dried (sodium sulfate) and evaporated. The crude was purified on a silica column using dichloromethane / methanol (97 : 3) as eluent to give 12.2 g of the sub-title product (yield 87 %). ¹H NMR (400 MHz, chloroform-das solvent and internal reference) δ(ppm) 1.46 (s, 9H), 3.24 (m, 2H), 3.58 (t, 2H, J= 5.2 Hz), 4.14 (s, 2H), 4.54 (s, 2H), 7.01 (d, 2H, J= 8.3 Hz), 7.66 (d, 2H, J= 8.4 Hz).

C) 3-Oxo-4-r4-f4,4,5,5-tetramethyl-ri,3,21dioxaborolan-2-γlVbenzvn-piperazine-l- carboxylic acid tert-butyl ester and (4-(r4-(tert-butoxycarbonyl)-2-oxopiperazin-l- yl Imeth yl } phenvDboronic acid

4-(4-Iodo-benzyl)-3-oxo-piperazine-l-carboxylic acid tert-butyl ester (9.5 g, 22.8 mmol) from step B, triethylamine (6.9 g, 68 mmol), and bis(tiiphenylphosphine)palladium- (EQchloride (506 mg, 0.720 mmol) was dissolved in 74 mL dry dioxane under argon atmosphere. Pinacolborane (4.38 g, 34.2 mmol) was added and the reaction was stirred at 100 ⁰C for 2 hours. Water and ethyl acetate was added. The organic phase was washed two times with water, once with brine, dried (sodium sulfate) and evaporated. The crude product was filtered through a silica column using ethyl acetate / heptane (60 : 40) as eluent. The crude was further purified by preparative HPLC using a gradient of acetonitrile 1 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate to give a mixture of the sub-title compound and the corresponding boronic acid. The mixture was used without further purification (3.48 g).

D) {4-[(2-Oxopiperazin-l-yl)methyllphenyl}boronic acid hydrochloride

To 3-oxo-4-[4-(4,4,5,5-tetramethyl-[l,3,2]dioxaborolan-2-yl)-benzyl]-ρiperazine-l- carboxylic acid tert-butyl ester and (4-{[4-(tert-butoxycarbonyl)-2-oxopiperazin-l- yl]methyl}ρhenyl)boronic acid (5.59 g, 13.4 mmol) from step C, as a mixture of boronic acid and boronic ester, was added 4 M hydrochloric acid in dioxane. The reaction mixture was stirred for 30 minutes. After evaporation of solvent in vacuo, water was added and the water phase was washed twice with dichloromethane. The water phase was evaporated and the residue was freeze dried over night to give 3.58 g of the desired sub-title product (98 % yield). ¹H NMR (400 MHz, methanol-^ as solvent and internal reference) δ (ppm) 3.52 (m, 4H), 3.93 (s, 2H), 4.68 (s, 2H), 7.33 (d, 2H, J = 8.0 Hz), 7.63 (m, 2H).

E) {4-[Y4-{ r5-Chloro-l-fρhenylsulfonyl^')-lH-indol-2-vπsulfonyl }-2-oxopiperazin-l- yPmethyllphenyUboronic acid

{4~[(2-Oxopiperazin-l-yl)methyl]phenyl}boronic acid (3.58 g, 15.3 mmol) from step D was dissolved in ΛT,N-dimethylformamide/water (45 mL, 6.6 mL ) and trietylamine (6.2 g, 61.2 mmol) was added. The reaction mixture was cooled to 0 °C and l-benzenesulfonyl-5- chloro-lH-indole-2-sulfonyl chloride (12.0 g, 30.6 mmol) dissolved in 30 mL iV,iV- dimethylformamide was added dropwise. The temperature was raised to room temperature over 2 hours. Water and ethyl acetate was added. The organic phase was washed four times with water, once with brine, dried (sodium sulfate) and evaporated. The crude product was further purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate to give 3.04 g of the sub-title compound (33 % yield).

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 3.33 (m, 2H), 3.72 (t, 2H, / = 5.4 Hz), 4.22 (s, 2H), 4.65 (s, 2H), 7.26 (m, 2H), 7.46-7.75 (m, 8H), 8.03 (d, 2H, /= 8.3 Hz), 8.24 (d, IH, J= 8.8 Hz).

F) { 4-IY4-I r5-chloro-lH-indol-2-yllsulfonvU-2-oxopiperazin-l-yl)methyllphenyl lboronic acid

To a solution of 200 mg of {4-[(4-{[5-chloro-l-(phenylsulfonyl)-lH-indol-2-yl]sulfonyl}- 2-oxopiperazin-l-yl)methyl]phenyl}boronic acid (0.34 mmol) from step E in 2 mL of N- methyl-2-pyrrolidone was added a solution of 98 mg of sodium hydroxide (2.4 mmol) in 2 mL of methanol at room temperature. After 2 hours stirring at room temperature, the reaction mixture was quenched with 1 mL of acetic acid. After removal of half amount of solvents, the resulting solution was loaded onto a reversed phase preparative ΗPLC column for purification. After freeze drying, 53 mg (35 %) of the sub-title product was obtained as a white powder.

¹H NMR (400 MHz; methanol-d₄ as solvent and internal reference) δ(pρm) 3.27 (m, s overlap with solvent peak, 2H), 3.43 (m, 2H), 3.93 (s, 2H), 4.49 (s, 2H), 7.00 - 7.06 (m, 3H), 7.28 (dd, IH, J = 8.8 Hz, /= 2.2 Hz), 7.40 (m, 3H), 7.67 (d, IH, /= 2.2 Hz).

G) 6-Chloro-2-(^'2-morpholin-4-yl-ethyl)-2H-pyridazin-3-one hydrochloride

6-Chloro-2H-pyridazin-3-one (5.34 g, 40.8 mmol), 7.61 g of 4-(2-chloro-ethyl)- o morpholine hydrochloride (40.8 mmol) and 11.3 g of potassium carbonate (81.7 mmol) were added to a solution of 20 niL of acetonitrile, 10 mL of iV,iV-dimethylformamide and 0.5 mL of water. The reaction mixture was heated with an oil bath at 116 ⁰C for 4 hours until LCMS showed the disappearance of 6-chloro-pyridazin-3-ol and the formation of the alkylated product. After cooling to room temperature, 100 mL of water was added to the s mixture. The aqueous phase was extracted twice with ethyl acetate. The combined organic phase was dried (sodium sulfate), concentrated in vacuo and the residue was subjected to flash column chromatography (ethyl acetate / hexane / triethyl amine, 1 : 6 : 0.05) on silica gel to give 6-chloro-2-(2-morpholin-4-yl-ethyl)-2H-pyridazin-3-one. Its hydrochloride salt was formed by adding 20 mL of 4 M aqueous hydrochloride solution and 20 mL of o methanol to the alkylation product until pH 2. The mixture was concentrated to get a solid residue, which was further purified by precipitation in hot ethanol. Finally, 4.23 g (37 %) of the sub-title product as a mono hydrochloride salt was obtained as colourless solids.

¹HNMR (400 MHz; methanol-d₄ as solvent and internal reference) δ(pρm) 3.24 (m, 2H), 5 3.64 (t, 3H, J = 5.8 Hz), 3.68 (m, 2H), 3.83 (m, 2H), 4.07 (m, 2H), 4.55 (t, 3H, J = 5.8 Hz), 7.06 (d, IH, J = 9.8 Hz), 7.56 (d, IH, /= 9.8 Hz).

m 6-Chloro-2-(2-morpholin-4-yl-ethyl)-2H-pyridazin-3-one hydrochloride (63 mg, 0.22 mmol) from step G; 78 mg of [4-({4-[(5-chloro-lH-indol-2-yl)sulfonyl]-2-oxopiperazin-l- yl }methyl)ρhenyl]boronic acid (0.17 mmol) from step F, 156 mg of caesium carbonate (0.48 mmol), and 11 mg of bis(triρhenylphosphine) palladium(II)chloride (0.02 mmol) were mixed in 2.0 mL of solvents mixture (dimethyl acetamide / water / ethanol, 7 : 3 : 2) in a microwave vial. The reaction heated in a microwave oven at 150 ⁰C for 150 seconds. After reaction, the mixture was first filtered, then purified by reversed phase preparative ΗPLC. After freeze drying, 71 mg (67 %) of the product was obtained as a white powder.

¹H NMR (400 MHz; 2V,iV-dimethylformamide-d₇ as solvent and internal reference) δ(ppm) 2.48 (m, 2H), 2.77 (m, 2H), 3.30 - 3.60 (m, 10H), 3.94 (s, 2H), 4.33 (t, 2H, J= 6.7 Hz), 4.62 (s, 2H), 7.03 (d, IH, J= 9.6 Hz), 7.18 (s, IH), 7.29 (m, 2H), 7.35 - 7.38 (m, IH), 7.59 (m, IH), 7.78 (m, 2H), 7.84 (m, IH), 8.01 (d, IH, /= 9.6 Hz).

HRMS (ESI+) calc. [M+H]⁺ 611.1838, found 611.1811.

Example 5

6-[4-({4-[(5-Chloro-lH-indol-2-yl)sulfonyl]-2-oxopiperazin-l-yl}methyl)phenyI]-2-[2- (methyIamino)ethyl]pyridazin-3(2H)-one hydrochloride

A) 6-Chloro-2H-pyridazin-3-one

To four microwave vials were added 3,6-dichloropyridazine (250 mg, 1.68 mmol), potassium acetate (165 mg, L68 mmol) and 5 mL acetic acid/ water (5 : 1). The reaction was heated at 140 ⁰C for 70 minutes. The vials were pooled and the solvent was evaporated in vacuo. The crude product was purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in a water buffer containing 0.1 M ammonium acetate, to give 748 mg of the sub-title compound (yield 85 %). ¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (pprn) 6.97 (d, IH, J = 9.7 Hz), 7.45 (d, IH, J = 9.8 Hz).

B) r2-(3-Chloro-6-oxo-6H-pyridazin-l-yl)-ethyll-carbamic acid tert-butyl ester A mixture of 6-chloro-2H-pyridazin-3-one (142 mg, 1.00 mmol) from step A, 2-(boc- amino) ethyl bromide (292 mg, 1.30 mmol) and potassium carbonate (180 mg, 1.30 mmol) in 5 mL acetonitrile was stirred at 80 ⁰C for 2 hours and over night at room temperature. The solvent was evaporated in vacuo and the residue was dissolved in ethyl acetate and filtered. The solvent was evaporated and the crude was purified on a silica column using ethyl acetate / heptane (1 : 1) as eluent to give 232 mg of the desired sub-title product (yield 77 %).

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 1.39 (s, 9H), 3.44 (t, 2H, / = 5.6 Hz), 4.17 (t, 2H, J = 5.1 Hz), 6.96 (d, IH, J = 9.S Hz), 7.42 (d, IH, J = 9.7 Hz).

C) r2-(3-Chloro-6-oxo-6H-pyridazin-l-yl)-ethvIl-methyl-carbamic acid tert-butyl ester

[2-(3-Chloro-6-oxo-6H-pyridazin-l-yl)-ethyl]-carbamic acid tert-butyl ester (330 mg, 1.20 mmol) from step B was dissolved in dry tetrahydrofuran and cooled on ice bath. Sodium hydride (43 mg, 1.8 mmol) was added in portions. After 10 minutes, iodomethane (257 mg, 1.8 mmol), dissolved in a small amount of tetrahydrofuran, was added over 10 minutes. The ice bath was removed and the reaction mixture was stirred over night at room temperature. Water and dichloromethane was added. The organic phase was separated, washed with water and brine, dried (sodium sulfate) and evaporated to give 284 mg of the sub-title product as light brown solids (yield 81 %).

¹H NMR (500 MHz, methanol-cU as solvent and internal reference) δ (ppm) 1.33 rotamers (s, 5H), 1.37 rotamers (s, 4H), 2.87 rotamers (m, 3H), 3.66 rotamers (m, 2H), 4.26 rotamers (m, 2H), 6.97 rotamers (m, IH), 7.46 rotamers (m, IH). D) N-[(5-chloro-lH-indol-2-yl)sulfonyl1-N-f2-U4-(dihvdroxyborvDbenzyllaminol- ethyl) glycine

{4-[(4-{[5-Chloro-l-(phenylsulfonyl)-lH-indol-2-yl]sulfonyl}-2-oxopiperazin-l- yl)methyl]phenyl}boronic acid (500 mg, 0.85 mmol) and 6 mL 2.5 M sodium hydroxide were mixed and warmed to 80 °C. After 20 minutes a solution was obtained and the reaction was cooled to room temperature. The reaction mixture was acidified and evaporated in vacuo. The residue was purified by preparative HPLC using a gradient of acetonitrile / 5% acetonitrile in water buffer containing 0.1 M ammonium acetate as eluent to give 202 mg (yield 53 %) of the sub-title compound.

¹H INMR (400, methanol-d₄ as solvent and internal reference) δ (ppm) 3.27 (m, 2H), 3.48 (m, 2H), 3.80 (s, 2H), 4.24 (s, 2H), 7.05 (s, IH), 7.28 (dd, IH, /= 2.0 Hz, 8.8 Hz), 7.44 (d, IH, / = 8.8 Hz), 7.53 (d, 2H, / = 7.S Hz), 7.68 (m, 3H).

E) r[2-(4-{ l-r2-(tert-Butoxycarbonyl-methyl-amino)-ethyl1-6-oxo-l,6-dihydro-ρyridazin- 3-yl}-benzylamino)-ethyl1-f5-chloro-lH-indole-2-sulfonyI)-amino1-acetic acid

To a microwave vial was addedN-[(5-chloro-lH-indol-2-yl)sulfonyl]-iV-(2-{[4- (dihydroxyboryl)benzyl] amino} ethyl) glycine (100 mg, 0.22 mmol) from step D, [2-(3- chloro-ό-oxo-βH-pyridazin-l-y^-ethyll-methyl-carbamic acid tert-butyl ester (77 mg, 0.26 mmol) from step C, bis(triphenylρhosphine)palladium(H)chloride (16 mg, 0.020 mmol) and caesium carbonate (87 mg, 0.26 mmol). The vial was evacuated and filled with nitrogen, two times. 1,2-Dimethoxyethane / water / ethanol (3 mL, 7 : 3 : 2) was added and the vial was again evacuated and filled with nitrogen. The reaction was heated at 150 °C for 100 seconds in a microwave oven. The reaction mixture was filtered and purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate, (C8-column) to give 72 mg of the sub-title compound after evaporation and freeze drying (47 % yield). ¹H NMR ( 400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 1.23 (s, 9H), 2.92 (s, 3H), 3.31 behind solvent peak (m, 2H), 3.50 (t, 2H, / = 5.3 Hz), 3.74 (m, 2H), 3.82 (s, 2H), 4.29 (s, 2H), 4.41 (t, 2H / = 5.3), 7.06 (m, 2H), 7.28 (dd, IH, J = 2.0, 8.7 Hz), 7.44 (d, IH, J = 8.8 Hz), 7.67 (m, 3H), 7.99 (m, 3H).

5

F) r2-(3-{4-r4-f5-Chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethvn-phenyl}-6- oxo-6H-pyridazin-l-yl)-ethyn-methyl-carbamic acid tert-butyl ester

[[2-(4-{l-[2-(tert-Butoxycarbonyl-methyl-amino)-ethyl]-6-oxo-l,6-dihydro-pyridazin-3- yl}-benzylamino)-ethyl]-(5-chloro-lH-indole-2-sulfonyl)-amino]-acetic acid (72 mg, 0.10 o mmol) from step E was dissolved in 3 mL N,N-dimethylformamide. Diisopropylethyl- . amine (41.5 mg, 0.321 mmol) and l-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (41 mg, 0.21 mmol) were added. The mixture was stirred at room temperature over night. A small amount of l-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and diisopropylethylamine was added and the mixture was s stirred for 4 days at room temperature. Ethyl acetate and water was added. The organic phase was separated and washed three times with water, once with brine, dried (sodium sulfate) and evaporated. The crude product was further purified with preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile-water phase containing 0.1 M ammonium acetate, C8-column, to give the sub-title product (35 mg, 49 % yield) after evaporation and 0 freeze drying over night.

¹H NMR (300 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 1.19 rotamers (s, 4H), 1.23 rotamers (s, 5H), 2.90 (s, 3H), 3.32 behind solvent peak (m, 2H), 3.50 (m, 2H), 3.73 (m, 2H), 4.00 (s, 2H), 4.41 (t, 2H, J = 5.3 Hz), 4.57 (s, 2H), 7.05 (m, 2H), 7.17 S (m, 2H), 7.28 (dd, IH, J = 2.0, 8.9 Hz), 7.44 (d, IH, / = 8.9 Hz), 7.67 (m, 3H), 7.93 (m, IH). G)

Hydrochloric acid in dioxane (4 M, 2 mL) was added to [2-(3-{4-[4-(5-chloro-lH-indole- 2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-6-oxo-6H-pyridazin-l-yl)-ethyl]-methyl- carbamic acid tert-butyl ester (35 mg, 0.050 mmol) from step F. The mixture was stirred at room temperature for 20 minutes. The solvent was evaporated in vacuo. The product was freeze dried over night to give 26 mg of the title compound (82 % yield).

¹H NMR (300 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 2.76 (s, 3H), 3.32 behind solvent peak (m, 2H), 3.52 (m, 4H), 4.00 (s, 2H), 4.58 (m, 4H), 7.05 (s, IH), 7.14 (d, IH, J = 9.7 Hz), 7.19 (d, 2H, J = 8.5 Hz) 7.28 (dd, IH, J = 2.0, 8.9 Hz), 7.44 (d, IH, J = 8.9 Hz), 7.70 (m, 3H), 7.99 (d, IH, J = 9.8 Hz).

HRMS (ESI+) calc. [M+H]⁺ 555.1576, found 555.1560.

Example 6

6-{4-[4-(5-ChIoro-lH-indσle-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2-(2- dimethylamino-ethyl)-2H-pyridazin-3-one

A) 6-Chloro-2-(2-dimethylamino-ethyl)-2H-pyridazin-3-one To a solution of 6-chloro-pyridazin-3-one (500 mg, 3.83 mmol) in 5 mL N,N- dimethylformamide was added 2-dimethylaminoethyl chloride hydrochloride (828 mg, 5.75 mmol), potassium carbonate (1.59 g, 11.5 mmol) and sodium iodide (632 mg, 4.21 mmol). The mixture was stirred over night at 65 ⁰C. The solvent was evaporated. The crude product was purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile-water phase containing 0.1 M ammonium acetate, to give 174 mg of the desired sub-title product as light brown solids after freeze drying (22 % yield). ¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 2.35 (s, 6H), 2.82 (t, 2H, J = 6.4 Hz), 4.26 (t, 2H, J = 6.5 Hz), 6.9S (d, IH, J = 9.7 Hz), 7.44 (d, IH. J = 9.7 Hz).

B) r(5-Chloro-lH-mdole-2-sulfonylV(2-{ 4-ri-(2-dimethylamino-ethylV6-oxo-l .6-dihvdro- pyridazin-3-yli-benzylaπrino }-ethyl)-amino^~|-acetic acid

To a microwave vial was addedN-[(5-chIoro-lH-indol-2-yl)sulfonyl]-N-(2-{[4- (dihydroxyboryl)benzyl] amino} ethyl) glycine (133 mg, 0.29 mmol), 6-chloro-2-(2- dimethylamino-ethyl)-2H-pyridazin-3-one (71.8 mg, 0.35 mmol) from step A, caesium carbonate (116 mg, 0.35 mmol) and bis(triphenylphosphine)palladium(ll)chloride (21 mg, 0.030 mmol). The vial was evacuated and filled with argon twice. 1,2-Dimethoxyethane / water / ethanol (4 mL, 7 : 3 : 2) was added and the vial was again evacuated and filled with argon. The reaction was heated at 150 °C for 80 seconds in a microwave oven. The mixture was filtered and purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate (C8-column) as eluent to give 138 mg (yield 79 %) of the desired sub-title compound after evaporation and freeze . drying.

¹H NMR (400 MHz, dimethyl sulfoxide-ds as solvent and internal reference) δ (ppm) 2.19 (s, 6H), 2.67 (t, 2H, J = 6.2 Hz), 2.96 (m, 2H), 3.29 behind solvent peak (s, 2H), 3.67 (s, 2H), 3.99 (m, 2H), 4.23 (t, 2H, J = 6.3 Hz), 6.98 (s, IH), 7.02 (d, IH, J = 9.7 Hz), 7.26 (dd, IH, J = 2.0 Hz, 8.8 Hz), 7.43 (d, IH, / = 8.8 Hz), 7.54 (d, 2H, J = 7.7 Hz), 7.72 (d, IH, / = 2.0 Hz), 7.88 (d, 2H, / = 7.7 Hz), 8.03 (d, IH, J = 9.6 Hz).

C)

To a solution of [(5-chloro-lH-indole-2-sulfonyl)-(2-{4-[l-(2-dimethylamino-ethyl)-6- oxo-ljδ-dihydro-pyridazin-S-ylJ-benzylaminoJ-ethy^-aminol-acetic acid (138 mg, 0.23 mmol) from step B in 6 mL iV.iV-dimethylformamide was added 4-dimethylaminopyridine (115 mg, 0.94 mmol) and l-ethyl-3-(3-dimethylarninopropyl) carbodiimide hydrochloride (90 mg, 0.47 mmol). The reaction was stirred for 4 hours at room temperature. The solvent was evaporated under reduced pressure. The crude product was purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate (C8-column) to give 53 mg of the title product as a light yellow powder after evaporation and freeze drying (yield 39 %).

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 2.53 (s, 6H), 3.10 (m, 2H), 3.31 behind solvent peak (m, 2H), 3.52 (t, 2H, / = 5.3 Hz), 4.00 (s, 2H), 4.48 (t, 2H_; / = 5.9 Hz), 4.57 (s, 2H), 7.04 (s, IH), 7.08 (d, IH / = 9.6 Hz), 7.16 (d, 2H, J = 8.3 Hz), 7.27 (dd, IH, J = 2.0 Hz, 8.8 Hz), 7.43 (d, IH, J = 8.8 Hz), 7.67 (m, 3H), 7.93 (d, IH, J = 9.7 Hz).

HRMS (ESI+) calc. [M+H]⁺ 569.1732, found 569.1760.

Example 7

2-(2-Amino-ethyl)-6-{4-[4-(5-chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l- yImethyl]-phenyI}-2H-pyridazin-3-one

A) r(2-{4-ri-(2-tert-Butoxycarbonylamino-ethyl)-6-oxo-l,6-dihydro-pyridazin-3-vn- benzylamino ) -ethyl)- (5-chloro- lH-indole-2-sulfonyl)-amino1-acetic acid

To a vial for microwaves was addedN-[(5-chloro-lH-indol-2-yl)sulfonyl]-N-(2-{[4- (dihydroxyboryl)benzyl]amino}ethyl)glycine (349 mg, 0.78 mmol), [2-(3-chloro-6-oxo- 6H-pyridazin-l-yl)-ethyl]-carbamic acid tert-butyl ester (256 mg, 0.93 mmol), caesium carbonate (305 mg, 0.93 mmol) and bis(triphenylphosphine)palladium(II)chloride (55 mg, 0.078 mmol). The vial was evacuated and filled with nitrogen, three times. 1,2-

Dimethoxyethane / water / ethanol (6.6 mL, 7 : 3 : 2) was added and the vial was again evacuated and filled with nitrogen, three times. The reaction was heated to 150 °C for 100 seconds. The mixture was filtered and purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate as eluent to give 482 rag (yield 93 %) of the sub-title compound.

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 1.32 (s, 9H), 3.23 (t, 2H, / = 5.4 Hz), 3.52 (m, 4H), 3.85 (s, 2H), 4.22 (s, 2H), 4.34 (t, 2H, / = 5.4 Hz), 7.07 (m, 2H), 7.30 (dd, IH, / = 2.0, 8.8 Hz), 7.47 (d, IH, J = 8.8 Hz), 7.65 (d, 2H, / = 8.3 Hz), 7.70 (d, IH, J - 2.0 Hz), 7.98 (d, 2H, J = 8.3 Hz), 8.02 (d, IH, / = 9.7 Hz).

B> r2-f3-{4-r4-(^'5-ChIoro-lH-indole-2-sulfonyl)-2-oxo-piρerazin-l-ylniethvn-phenyl}-6- oxo-όH-pyridazin-l-yD-ethyli-carbamic acid tert-butyl ester

To a solution of [(2-{4-[l-(2-tert-butoxycarbonylamino-ethyl)-6-oxo-l,6-dihydro- pyridazin-3-yl]-benzylamino}-ethyl)-(5-chloro-lH-indole-2-sulfonyl)-amino]-acetic acid (482 mg, 0.73 mmol) from step A in 15 mL iV,N-dimethylformamide was added 4- dimethylaminopyridine (358 mg, 2.93 mmol) and l-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (281 mg, 1.47 mmol). The reaction was stirred at room temperature over night. The reaction mixture was washed with 5 % hydrochloric acid and then ethyl acetate and water was added. The organic phase was washed three times with water, once with brine, dried (sodium sulfate) and evaporated. The crude was filtered on a silica column using ethyl acetate as eluent, the crude was further purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate as eluent to give 155 mg (yield 33 %) of the sub-title compound after freeze drying.

¹H NMR (400 MHz, methanol-d₄ as solvent and internal reference) δ (ppm) 1.27 (s, 9H), 3.31 behind solvent peak (m, 2H), 3.51 (m, 4H), 3.99 (s, 2H), 4.33 (t, 2H, / = 5.7 Hz), 4.57 (s, 2H), 7.04 (m, 2H), 7.16 (d, 2H, J = 8.3 Hz), 7.28 (dd, IH, / = 2.0, 8.8 Hz), 7.43 (d, IH, J = 8.8 Hz), 7.69 (m, 3H), 7.90 (d, IH, J = 9.7 Hz). C]

To [2-(3-{4-[4-(5-chloro-lH-indole-2-sulfonyl)-2-oxo-ρiperazin-l-ylmethyl]-phenyl}-6- oxo-6H-pyridazin-l-yI)-ethyl]-carbamic acid tert-butyl ester (155 mg, 0.24 mmol) from step B was added 4 M hydrochloric acid in dioxane. The mixture was stirred at room temperature for 30 minutes. The solvent was evaporated and the residue was freeze dried. The crude was purified on a C8-column using a gradient of acetonitrile / water. The product was eluted with methanol and further purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate as eluent to give 122 mg (yield 93 %) of the title product after freeze drying.

¹H NMR (500 MHz, methanol-d^. as solvent and internal reference) δ (ppm) 3.34 (m, 2H), 3.40 (t, 2H, J = 5.6 Hz), 3.53 (t, 2H, J = 5.6 Hz), 4.01 (s, 2H), 4.52 (t, 2H, / = 5.9 Hz), 4.59 (s, 2H), 7.06 (s, IH), 7.13 (d, IH, J = 9.7 Hz), 7.20 (d, 2H, J = 8.4 Hz), 7.30 (dd, IH, J = 2.0 Hz, 8.8 Hz), 7.45 (d, IH, J = 8.8 Hz), 7.71 (m, 3H), 7.99 (d, IH, J = 9.6).

HRMS (ESI+) calc. [M+H]⁺ 541.1419, found 541.1437.

Example 8

6-{4-[4-(5-ChIoro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2H- pyridazin-3-one

A) 4-(5-Chloro-lH-indole-2-sulfonyl)-l-r4-(6-chloro-pyridazin-3-yl)-benzyll-piperazin-2- one

N-[(5-Chloro-lH-indol-2-yl)sulfonyl]-N-(2-{[4-(dihydroxyboryl)benzyl]- amino }ethyl)glycine (100 mg, 0.22 mmol), 3,6-dichloropyridazine (39.9 mg, 0.27 mmol), caesium carbonate (87 mg, 0.27 mmol) and bis(triphenylphosphine)palladium(H)chloride (16 mg, 0.020 mmol) was added to a microwave vial. The vial was evacuated and filled with nitrogen, three times. 1,2-Dimethoxyethane / water / ethanol (2.5 mL, 7 : 3 : 2) was added. The vial was again evacuated and filled with nitrogen. The reaction was heated at 150 ⁰C for 100 seconds in a microwave oven. As the starting material was not consumed a small amount of catalyst was added and the vial was again evacuated. The reaction was heated again at 150 ⁰C for 100 seconds. The crude was filtrated and purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate to give 27 mg of the sub-title product after freeze drying over night (yield 23 %).

¹HNMR (500 Hz, dimethyl sulfoxide-dβ as solvent and internal reference) δ (ppm) 3.28 (m, 2H), 3.45 (t, 2H, J = 5.3 Hz), 3.90 (s, 2H), 4.55 (s, 2H), 7.08 (s, IH), 7.27 (m, 3H), 7.49 (d, IH, J = 8.4 Hz), 7.76 (s, IH), 7.94 (d, 2H, / = 8.5 Hz), 8.01 (d, IH, / = 8.5 Hz), 8.25 (d, IH, / = 8.5 Hz).

B)

To a microwave vial was added 4-(5-chloro-lH-indole-2-sulfonyl)-l-[4-(6-chloro- pyridazin-3-yl)-benzyl]-piperazin-2-one (27 mg, 0.05 mmol) from step A, potassium acetate (26 mg, 0.26 mmol) and 1 mL of acetic acid / water (5 : 1). The reaction was heated to 150 ⁰C for 15 minutes in a microwave oven. The solvent was evaporated and the residue was purified by preparative HPLC using a gradient of acetonitrile / 5 % acetonitrile in water buffer containing 0.1 M ammonium acetate to give 22 mg of the title product after freeze drying (yield 84 %).

¹H NMR (400 Hz, dimethyl sulfoxide-d₆ as solvent and internal reference) δ(ppm) 3.22 (m, 2H), 3.42 (t, 2H, / = 5.4 Hz), 3.87 (s, 2H), 4.48 (s, 2H), 6.96 (d, IH, J = 9.1 Hz), 7.07 (s, IH), 7.14 (d, 2H, J = 8.3 Hz), 7.30 (dd, IH, / = 2.0 Hz, 8.8 Hz), 7.47 (d, IH, / = 9.7 Hz), 7.62 (d, 2H, / = 8.4 Hz), 7.75 (d, IH, J = 2.0 Hz), 7.92 (d, IH, J = 9.8 Hz).

HRMS (ESI+) calc. [M+H]⁺ 498.0998, found 498.1007.

Claims

1. A compound of formula (I)

⁽0

wherein R¹ is hydrogen, C_1-3alkyl, R⁵R⁶aminoC_1-5alkyl, where R⁵ and R⁶ are each independently selected from hydrogen and C_1-3alkyl, or

R⁵ and R⁶ may, together with the nitrogen to which they are attached, form a five- or six- membered heterocyclic ring, where said heterocyclic ring has 0 or 1 additional heteroatom; n is 1 or 2; each R² are independently selected from hydrogen, oxo and Ci_-3alkyl, R³ is an indolyl, and

R⁴ a hydrogen or a halogen; or a pharmaceutically acceptable salt thereof.

2. A compound according to claim 1 wherein R¹ is hydrogen.

3. A compound according to claim 1 wherein R¹ is C^alkyl, e.g. propyl, ethyl or methyl.

4. A compound according to claim 1 wherein R¹ is R⁵R⁶aminoC_1-3alkyl, where R⁵ and R⁶ are each independently selected from hydrogen and Ci_-3alkyl, e.g. propyl, ethyl or methyl, or

R⁵ and R⁶ may, together with the nitrogen to which they are attached, form a six-membered heterocyclic ring, where said heterocyclic ring has 1 additional hetero oxygen.

5. A compound according to anyone of claims 1 to 4 wherein one of R² is oxo.

6. A compound according to anyone of claims 1 to 5 wherein one of R² is C_1-3alkyl.

7. A compound according to anyone of claims 1 to 6 wherein R³ is 2-indolyl or 6-indolyl.

8. A compound according to anyone of claims 1 to 7 wherein R⁴ is chloro.

9. A compound according to claim 1 which is 6-{4-[S)-4-(3-chloro-lH-indole-6-sulfonyl)-2-methyl-6-sulfonyl)

-2-methyl-6-oxo-piperazin-l-ylmethyl]-phenyl}-2-methyl-2H-pyridazin-3-one,

6- { 4- [(S)-4-(5-Chloro- lH-indole-2-sulf onyl)-3-methyl-2-oxo-piperazin- 1 -y lmethyl]- phenyl } -2-methyl-2H-pyridazin-3-one,

6-{4-[(S)-4-(5-Chloro-lH-indole-2-sulfonyl)-2-methyl-6-oxo-piperazin-l-ylmethyl]- phenyl }-2-methyl-2H-pyridazin-3-one,

6- {4-[4-(5-Chloro- lH-indole-2-sulfonyl)-2-oxo-piperazin-l-yImethyl]-phenyl } -2-(2- morpholin-4-yl-ethyl)-2H-pyridazin-3-one,

6-[4-({4-[(5-Chloro-lH-indol-2-yl)sulfonyl]-2-oxopiρerazin-l-yl}methyl)phenyl]-2-[2-

(methylamino)ethyl]pyridazin-3(2H)-one hydrochloride, 6-{4-[4-(5-Chloro-lH-indole-2-sulfonyl)-2-oxo-piperazin-l-ylmethyl]-phenyl}-2-(2- dimethylamino-ethyl)-2H-pyridazin-3-one,

2-(2- Amino-ethyl)-6- { 4- [4-(5 -chloro- lH-indole-2-sulf onyl)-2-oxo-piperazin- 1 -ylmethyl] - phenyl }-2H-pyridazin-3-one or

6- { 4-[4-(5-Chloro- lH-indole-2-sulf onyl)-2-oxo-piperazin- 1 -ylmethyl] -phenyl } -2H- pyridazin-3-one.

10. A process for preparing a compound of formula (I) as defined in claim 1 which process comprises either

(a) intramolecularly reacting an amino acid of formula (II) or a salt thereof,

in the presence of a suitable base and a acid activating agent such as a carbodiimide; (b) reacting a compound of the formula (IH):

(III) wherein Z' is a displaceable group such as halo or sulfonate, with a compound of formula (IV),

(IV) wherein A is an activating group;

(c) reacting a compound of the formula (VI),

(Vl) when X is a halogen, by hydrolysing or, when X is an alkoxy group, by dealkylating; or

(d) reacting a sulfonyl chloride derivative of formula (VII),

CI— SO^-R-R⁴

(VII) with an amine of formula (VIII),

(VIII) or a salt thereof.

11. A compound of formula (I), as defined in any claim from 1 to 9, or a pharmaceutically-acceptable salt thereof for use in medical therapy.

12. A pharmaceutical composition comprising a compound of formula (I), or a pharmaceutically-acceptable salt thereof, as defined in any claim from 1 to 9, with a pharmaceutically-acceptable diluent or carrier.

13. Use of a compound of formula (I), as defined in any claim from 1 to 9, or a pharmaceutically-acceptable salt thereof, in the preparation of a medicament for use in a method of treating a Factor Xa mediated disease or condition.

14. A method of treating a Factor Xa mediated disease or condition in a warm-blooded animal comprising administering an effective amount of a compound of formula (I), as defined in any claim from 1 to 9, or a pharmaceutically-acceptable salt thereof.

15. A combination comprising a compound of formula (I), as defined in any claim from 1 to 9, or a pharmaceutically-acceptable salt thereof, and any antithrombotic agent(s) with a different mechanism of action, wherein said antithrombotic agent(s) may be, for example, one or more of the following: the anticoagulants unfractionated heparin, low molecular weight heparin, other heparin derivatives, synthetic heparin derivatives (e.g. fondaparinux), vitamin K antagonists, synthetic or biotechnological inhibitors of other coagulation factors than FXa (e.g. synthetic thrombin, FVIIa, FXIa and FIXa inhibitors, and rNAPc2), the antiplatelet agents acetylsalicylic acid, ticlopidine and clopidogrel; thromboxane receptor and/or synthetase inhibitors; fibrinogen receptor antagonists; prostacyclin mimetics; phosphodiesterase inhibitors; ADP-receptor (P2X1, P2Y1, P2Y12 [P2T]) antagonists; and inhibitors of carboxypeptidase U (CPU or TAFIa) and inhibitors of plasminogen activator inhibitor- 1 (PAI-I).

16. A combination comprising a compound of formula (I), as defined in any claim from 1 to 9, or a pharmaceutically-acceptable salt thereof, and thrombolytics, e.g. one or more of tissue plasminogen activator (natural, recombinant or modified), streptokinase, urokinase, prourokinase, anisoylated plasminogen-streptokinase activator complex (APSAC), animal salivary gland plasminogen activators.