DD247003A1 - PROCESS FOR PREPARING IN 2-POSITION WITH AMN-CONTAINING GROUPS SUBST. 7 H-1,3,4-THIADIAZOLO (3,2-A) PYRIMIDINES - Google Patents

Abstract

The invention relates to a process for the preparation of 7H-1,3,4-thiadiazolo (3,2-a) pyrimidines which are substituted in the 2-position with amine-containing groups and are used for the therapy of ischemic cardiovascular diseases or as antithrombotics can. According to the invention, a cyclization of the correspondingly substituted 1-acylamino-2-thioxo-1,2,3,4-tetrahydropyrimidines in the presence of polyphosphoric acid is carried out at temperatures of 90 to 95C.

Description

Field of application of the invention ^v

The invention relates to a preparation process for N-substituted or N-substituted 2- (aminophenyl) -, 2- (phenylaminomethyl) -, 2- (phenyl-methyl-amino-methyl) -, - 2- (Älky] -amino-methyl ), 2- (aminophenoxy-methyl) -, 2- (aminophenyl-methyl) -, 2- (nitro-phenyl-amino-methyl) - and 2- (amino-phenyl-amino-methyl) -7H-1, 3,4-thiadiazolo (.3,2-a) -pyrimidirie, which can be used for the therapy of ischemic cardiovascular diseases and as antithrombotics and are effective as a Ca antagonist and as cAMP-cleaving phosphodiesterase inhibitors.

Characteristic of the known technical solutions

1,3,4-thiadiazolo (3,2-a) pyrimidines were first reported in 1959 (C.F.H. Allen and coworkers: J. Org. Chem., 24, 779 [1959]).

Differently substituted, the following structure types exist:

5H-1,3,4-thiadiazolo (3,2-a) -pyrimidin-5-one or -thione, 7H-1,3,4-thiadiazolo (3,2-a) pyrimidin-7-one, 1, 3,4-thiadiazolo (3,2-a) pyrimidinium salts, mesoionic 1,3,4-thiadiazolo (3,2-a) pyrimidines "and 2-alkyl, 2-cycloalkyl, 2-phenyl, 2 ( Halophenyl), 2- (nitrophenyl) -2- (methoxyphenyl), '2-phenoxymethyl and 2- (halophenoxymethyl) -7H-1,3,4-thiadiazolo (3,2-a) pyrimidines.

For synthesis two principles are known:

It is assumed that a 2-amino-1,3,4-thiadiazole and the pyrimidine ring is fused by reaction with a 1,3-bifunctional C ₃ -Bäustein.

It is started from an N-amino or N-acylamino-pyrimidin-2-thione and the Thiadiazolring is closed by reaction with a carboxylic acid or a carboxylic acid derivative or by dehydration.

The first synthetic route is not suitable for the preparation of 7H-1,3,4-thiadiazolo- (3,2-a) pyrimidines. These compounds were first prepared in 1978 (eg Chem., 18, 66 [1978]) by cyclizing dehydration of 4,4,6-trialky substituted 1-acylamino-2-thioxo-1,2,3,4-tetrahydro-pyrimidines , An improved method (DD-WP 200741/0, C07 D513 / 04, 08.06.1983) uses H ₂ SO ₄ as condensing agent, but it can easily lead to the sulfonation of the 5-methyl group and the possibly present aryl substituent in 2-Steliung.

Object of the invention

The aim of the invention is to develop a process for the preparation of substituted in 2-position with amine-containing groups 7 H-1,3,4-thiadiazolo (3,2-a) pyrimidines.

Explanation of the essence of the invention

This problem, 7 H-1,3,4-thiadiazolo (3,2-a) pyrimidines of the general formula:

in which R can denote an aminophenyl-dimethylaminophenyl, aminophenylmethyl, phenylaminomethyl, diethylaminomethyl, phenylmethyl-methylaminomethyl, aminophen oxy methyl or aminophenylaminomethyl group, the invention is achieved by carrying out the cyclization of the corresponding 1-acylamino 2-thioxo-1,2,3,4-tetrahydropyrimdine by means of polyphosphoric acid at 90 to 95 ° C.

Embodiment <.

The substituted in 2-position with amine-containing groups 7 H-1,3,4-thiadiazolo (3,2-a) pyrimidines are as follows. general production instructions are shown:

0.02 mol of the corresponding 1-acylamino-1,2,3,4-tetrahydropyrimidine are finely pulverized with 40 mol of polyphosphoric triturated and with exclusion of moisture and repeated shaking at 95 ⁰ C until a clear, colorless solution is formed (about 2 hours' ). It is taken up with stirring and cooling (T <25 ° C) in 200 ml of water. Which occurs when the dropwise addition of conc. Ammonia (T <25 ⁰ C) to pH 8 separating Thiadiazolo-pyrimidine is extracted with ether or methylene chloride, the extract washed with water and the solvent removed in vacuo. The residue is purified by recrystallization or vacuum distillation.

Table 1

7H-1,3,4-thiadiazolo (3,2-a) pyrimidines substituted in 2-position with amine-containing groups (I)

IR Fp / | _mml bp. ° C yield in%

a 0 -NH ₂ C ₆ H ₄ 255.5-258 58

b 'm -NH ₂ -C ₆ H ₄ . 161-164 ^- 71

c P-NH ₂ -C ₆ H ₄ 173.5-177.5 67

'P- (CH ₃ J ₂ NC ₆ H ₄ ' 109-111.5 83

e "P-NH ₂ -C ₆ H ₄ -CH ₂ 98-101.5 63

f C ₆ H ₅ -NH-CH ₂ resin 96

g (C ₂ H ₅ J ₂ N-CH ₂ 125-128 · '61

h C ₆ H ₅ -CH ₂ -N (CH ₃ J-CH _{2 (2)} 214 '31

i P -NH ₂ -C ₆ H ₄ -O-CH ₂ 100-105.5 11

j mN H ₂ -C ₆ H ₄ -NH-CH ₂ Resin 51

applications

The novel compounds (I) are distinguished by a broad spectrum of interesting pharmacodynamic effects which make them suitable for the treatment of ischemic cardiovascular diseases or as antithrombotics.

In animal experiments, in addition to coronary dilating and positive inotropic effects, a distinct, well-known compounds with the same mode of action, significantly superior inhibition of platelet aggregation has been demonstrated both in vitro and under in vivo conditions. The new compounds proved to be Ca antagonists and strong inhibitors of cAMP-cleaving phosphodiesterase.

The example of the 2-p-amino-phenyl-5,7,7-trimethyl-7H-1,3,4-thiadiazolo- (3,2-a) pyrimidine (Ic) is shown which effects the novel compounds achieve :

1. Inhibition of platelet aggregation in vitro

Platelets of the rat were separated and suspended in Michaelis buffer (pH 7.4) and defibrinated homologous plasma (1: 1).

To 1.2 ml of this platelet suspension 10 / xl preparation solution in ethanol were added and after 2 min. Preincubation at 37 ⁰ C, the aggregation by addition of arachidonic acid (2mmol / l final concentration in the cuvette) started. The measurement of platelet aggregation was carried out nephelometrically by the method of BORN (Born, VR and Gross UJ: J. Physiol., 186, 178)

To characterize the efficacy, the negative logarithm of the mean molar inhibitory concentration (plC ₅₀ ) was determined.

PlC ₅₀ ic 4.75 Trapidil 2.49

Compared to the known drug Trapidil, the new compound Ic proves to be about 10 times more effective.

2. Inhibition of platelet aggregation in vivo. ·

Intravenous administration of arachidonic acid in the rabbit causes intravascular platelet aggregation, especially in the pulmonary vessels, asphyxia and lethal effects.

Even in low, asymptomatically tolerated concentrations, the aggregative effect of arachidonic acid can be quantitatively determined on the basis of a transient reduction in the number of freely circulating platelets in the peripheral blood which can be demonstrated immediately after the injection, and the effectiveness of previously administered active substances can be demonstrated. In non-anesthetized rabbits, after blood extraction from the ear vein, the number of platelets was determined by means of phase contrast microscopy. Subsequently, arachididonic acid Na was administered at a dose of 0.1 mg / kg i. v. injected and the platelet counts V2,1,2,3, 5 and 10 min. then determined again. As a quantitative criterion for the ararchidonic acid-induced thrombocytopenia, the area enclosed by the percentage reduction in the number of platelets was planimetrically evaluated and its value for the control group was set to 100%.

To test the in vivo activity of the compound Ic, after determination of the individual unimpaired arachidonic acid reaction, it was per orally administered as a suspension in ultra-swellable cellulose by means of a flexible oesophageal tube and, in the manner described above, the extent of thrombocytopenia 1,2,4,6 and 24 h again determined after preparation.

The doses of the Ic or of the known comparator medicinal products Trapidil and acetylsalicylic acid were determined by which a 50% inhibition of arachidonic acid-induced thrombocytopenia was achieved (ED ₅₀ ).

ED ₅₀ mg / kg p.o. ic 3.7 Trapidil 21.5 acetylsalicylic acid 33.0

The new compound Ic confirmed its high efficacy against platelet aggregation even under in vivo conditions and in particular after peroral application and was clearly superior to known comparison preparations.

3. Korornardilatation,

The investigations were carried out on isolated after Langendorff perfused heart of the guinea pig.

The hearts were perfused in a thermostated chamber at 37 ° C and a pressure of 8 kPa with oxygen-fumed Tyrodelösung (pH 7.4). The measurement of the contractions was carried out with a strain gauge, the coronary flow was detected by means of pitot tube and pressure gauge administration of the test compound was carried out in single doses immediately before the

Perfusion solution in the heart. ,

Ic increases coronary flow at the isolated heart, this effect being more pronounced compared to trapidil.

Durchflußerhöhung

dose dl mg in ic 0.05 48 Trapidil 0.10 43

The heart rate is not significantly affected by Ic while the cardiac contraction force (dp / dt) is increased to about the same extent as the control drug Trapidil

4. Ca ²⁺ antagonist activity

Known Ca ²⁺ -antagonistically active compounds inhibit BaCI ₂ -induced spasms of isolated hay preparations. In order to demonstrate relevant effects of the new compound Ic, the influence on the BaCl ₂ (3 × 10 ^-3 M / l) induced contractions was investigated on the guinea pig ileum in vitro in the arrangement according to MAGNUS, 3 cm long, from the terminal part of the ileum harvested organ preparations were suspended in Tyrode solution at 35 ° C while passing in oxygen and detects the contractions by CPR-displacement transducer and recorded. the ED ₅₀ was determined that drug dose that reduced the BACI ₂ Effect on 50%.

-log ED ₅₀ ic 5.02 Trapidil 2.84

The high potency of the Ic compared to the Trapidil makes this new compound also interesting in terms of a possible Caantagonistischen effectiveness.

5. Phosphodiesterase inhibition

The activity of cAMP-cleaving phosphodiesterase (PDE) was determined according to BUTCHER et al. SUTHERLAND (Butcher, R.W., and E.W.Sutherland: J. Biol. Chem., 237, 1 244 [1962]).

The batch (0.9 ml) had the following composition:

1.8 mM MgSO ₄ , 36 mM TRIS, 0.5 mM cAMP (Boehringer, Mannheim). The reaction proceeded at pH 8.0 and 37 ° C and was stopped after 10 min by heating in the boiling water bath for 1 min. Thereafter, 0.1 ml of nucleotidase solution (Crotaius atrox, Sigma USA) was added and incubated at 37 ⁰ C for a further 10 min. To determine the cleaved orthophosphate, the incubation was stopped by addition of 0.1 ml of 5 η HCIO ₄ and, after centrifugation, the phosphate according to ALLEN (Allen, RIL:

Biochem. J. 38, 858 [1940]).

The new compound Ic proved in these studies as a strong inhibitor of cAMP-cleaving Ph osphieste rase, the following inhibition constants were determined:

Inhibition constant Κ; • ic '1.2 x 10 " ⁵ m

Trapidil. 1.3 χ 10 "" ³ sts

Claims (1)

Invention claim: Process for the preparation of in-2-methyl-substituted 7H-1,3-4-thiadiazolo (3,2-a) pyrimidines of the general formula  Λ, in which R can be an aminophenyl, dimethylaminophenyl, aminophenylmethyl, aminophenylaminomethyl, phenylaminomethyl, phenylmethyl-methylaminomethyl, aminophenoxymethyl and diethylamino-methyl group, characterized in that the cyclization of the corresponding 1-acylamino-2-thioxo -1,2,3,4-tetrahydropyrimidines in the presence of polyphosphoric acid at temperatures of 90 to 95 ° C.