WO2009035307A2

WO2009035307A2 - Novel compounds, process for preparing the same, and composition comprising the same for inhibiting pain

Info

Publication number: WO2009035307A2
Application number: PCT/KR2008/005439
Authority: WO
Inventors: Hae-Young Park Choo; Heung Sik Na; Hyewhon Rhim; Yoo Lim Kam; Seung Keun Back
Original assignee: Ewha Womans University
Current assignee: Ewha Womans University
Priority date: 2007-09-14
Filing date: 2008-09-12
Publication date: 2009-03-19
Anticipated expiration: 2010-03-14
Also published as: KR101079459B1; KR20090028239A; WO2009035307A3

Abstract

The present invention relates to novel compounds, a process for preparing the same, and a pain relief composition, comprising the same. The compound of the present invention has excellent inhibitory effect on T-type calcium channel activity, and chronic neuropathic and inflammatory pain, thereby being used to relieve pain.

Description

[DESCRIPTION]

[invention Title]

Novel compounds, process for preparing the same, and composition comprising the same for inhibiting pain

[Technical Field]

The present invention relates to novel compounds, a process for preparing the same, and a pain relief composition comprising the same.

[Background Art]

Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. Pain is the main symptom of various diseases, but pain perception is very subjective. Thus, pain is one of the most difficult pathologies to diagnose and treat effectively. Pain causes severe damage to functional ability, and threatens the patient' s work, social life, and family life.

Pain is classified into acute pain, and chronic pain such as neuropathic pain.

Acute pain is generally caused from inflammation and soft tissues damage. The neuronic mechanism causing acute pain is well known in the art, and thus the pain can be treated by analgesics such as nonsteroidal anti-inflammatory drug (NSAID) , opium products, etc., that are currently in market.

Chronic neuropathic pain is caused by injury to peripheral sensory nerves, and is very difficult to treat because the degree of pain is extremely severe, and the pain frequently recurs despite use of common analgesics such as opium products.

Neuropathic pain may be caused by various diseases, such as a herpes viral infection, diabetes mellitus, causalgia, plexus avulsion, neuroma, limb amputation, vasculitis, chronic alcoholism, human immunodeficiency virus infection, hypothyroidism, uremia, and vitamin deficiencies, in addition to peripheral sensory nerves damage.

Neuropathic pain may be classified into three types; hyperalgesia, allodynia, and spontaneous pain. "Hyperalgesia" is an excessive pain above a normal level. "Allodynia" is a pain caused by delicate response to such a slight extent of stimuli that normally it cannot induce pain. And, "spontaneous pain" is a pain felt though there is no stimulus . For example, allodynia includes mechanical allodynia that is a pain felt by weakmechanical stimuli, and cold/warm allodynia that is a pain felt by a certain range of temperature change that normally is not perceived as unpleasant .

Analgesics currently inmarket are classified into two kinds : one is nonsteroidal antiinflammatory drug (NSAID) and COX-2 inhibitors related thereto, and the other is opium products like morphine. These analgesics are effective for controlling common pain. However, they are of little effect against a certain type of pain like neuropathic pain. Some pain-relieving effect may be only achieved by administrating a high dose of opiates, which could cause serious side effects and addiction. In particular, NSAID has less pain-relieving effects, and thus should be used by in a higher dose than opiates to be effective. Also, in this case, an irritation to the gastrointestinal tract peculiarly caused by NASID may be accompanied.

Therefore, new compounds capable of controlling neuropathic pain by different mechanisms from analgesics known in the art, or uses thereof, have been urgently needed. A representative example of target materials for inventions of such compounds is an ion channel blocker. A voltage-gated calcium channel, in particular, N-type or T-type calcium channel, is known to regulate the excitability of dorsal horn neurons in the spinal cord, and is involved in the generation and maintenance of neuropathic pain. Gabapentin and pregabalin, currently used for the treatment of neuropathic pain, are also known to act on the voltage-gated calcium channel. Sodium channel blockers such as carbamazepine inhibit initiation and propagation of action potentials to exert analgesic effects.

[Disclosure] [Technical Problem]

Accordingly, the present inventors have studied compounds which block calcium channels to relieve pain, and also prepared compounds capable of effectively inhibiting T-type calcium channel activity. They found that the compounds had excellent inhibitory effects on chronic neuropathic pain and inflammatory pain, thereby completing the present invention.

[Technical Solution] It is an object of the present invention to provide compounds having excellent inhibitory effects on pain as calcium channel blockers, a process for preparing the same, and a pain relief composition comprising the same.

[Description of Drawings]

FIG. 1 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Preparation

Example 5) on chronic neuropathic pain (A: mechanical allodynia,

B: cold allodynia, C: warm allodynia); FIG. 2 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Example 2) on chronic neuropathic pain (A: mechanical allodynia, B: cold allodynia, C: warm allodynia);

FIG. 3 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Preparation

Example 5) on inflammatory pain;

FIG. 4 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Example 1) on inflammatory pain; FIG. 5 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Example 2) on inflammatory pain; and

FIG. 6 is a schematic drawing illustrating the relieving effect of the composition of the present invention (Example 3) on inflammatory pain.

[Best Mode]

The present invention provides a compound represented by the following Formula 1. <Formula 1>

wherein Ri is hydrogen; straight or branched Ci~Cio alkyl; CH₂-C₃-Ci₀ cycloalkyl; or benzyl substituted or unsubstituted with one or more groups selected from the group consisting of straight or branched Ci~Cio alkyl, Ci-C₄ alkoxy, halogen, nitro and N (CH₃) ₂,

R₃ and R₄ are each independently C₆-C₂₀ aryl or halogen-substituted C₆-C_2O aryl,

R₅ and R₆ are each independently hydrogen; C₆~C₂o aryl substituted with one or more groups selected from p-tolyloxy and Ci-C₄ alkyl; or CH(C₆-C_2O aryl) (halogen-substituted C₆-C₂O aryl), and n is an integer of 1 to 5. Preferably, in ' Formula 1,

Ri is hydrogen; ethyl; isobutyl; 2-ethylbutyl; CH₂-cyclohexyl; or benzyl substituted or unsubstituted with one or more groups selected from the group consisting of isopropyl, methoxy, Cl, nitro and N (CH₃) _2l

R₃,

\

CH N N»ΛΛΛ

/ \_/

R₂ is or NR₅R₆,

R₃ and R₄ are each independently phenyl or 4-chlorophenyl, R₅ and Re are each independently hydrogen, (p-tolyloxy) -phenyl, CH (phenyl) (4-chlorophenyl), or 2, 6-dimethylphenyl, and n is an integer of 3.

Preferred compounds among the compounds of Formula 1 of the present invention are as follows:

D

4 -amino-1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one,

2) 4-amino-N- (4-p-tolyloxy) phenyl) butanamide, 3) 4-amino-N- ( (4-chlorophenyl) (phenyl) methyl) butanamide, 4 ) 4-amino-N- (2 , 6-dimethylphenyl) butanamide, 5)

1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (ethy lamino) butan-1-one, 6) 1- (4- ( (4-chlorophenyl) (phenyl ) methy1 ) piperazin-1-yl) -4- (cycl ohexylmethylamino) butan-1-one,

7)

4- (4- (dimethylamino) benzylamino) -1- (4- ( (4-chlorophenyl) (phen yl) methyl ) piperazin-1-yl) butan-1-one,

8)

1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (isob utylamino) butan-1-one,

9) 4- (2-ethylbutylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) p iperazin-1-yl) butan-1-one,

10)

4- (benzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperaz in-1-yl) butan-1-one, 11)

4- (4-methoxybenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methy 1) piperazin-1-yl) butan-1-one,

12)

4- (4-nitrobenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one,

13)

4- (4-isopropylbenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl)met hyl) piperazin-1-yl) butan-1-one, and

14) 4- (2, 6-dichlorobenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl)me thyl) piperazin-1-yl) butan-1-one. The compounds of Formula 1 of the present invention may be prepared in the form of a pharmaceutically acceptable salt, solvate, or hydrate according to the conventional method in the related art. As the pharmaceutically acceptable salt, acidaddition salts produced with free acids are preferred. As the free acids, organic acids and inorganic acids may be used. Examples of the inorganic acids may include hydrochloric acid, bromic acid, sulfuric acid, and phosphoric acid, and examples of the organic acids may include citric acid, acetic acid, lactic acid, tartaric acid, fumaric acid, formic acid, propionic acid, oxalic acid, trifluoroacetic acid, methane sulfonic acid, benzene sulfonic acid, maleic acid, benzoic acid, gluconic acid, glycolic acid, succinic acid, 4-morpholine ethane sulfonic acid, camphorsulfonic acid, 4-nitrobenzene sulfonic acid, hydroxyl-O-sulfonic acid, 4-toluene sulfonic acid, galacturonic acid, embonic acid, glutamic acid and aspartic acid.

In addition, the present invention provides a process for preparing the compound represented by Formula 1, comprising the steps of

1) performing a condensation reaction of an amine compound represented by the following Formula 2 and a compound represented by the following Formula 3 to prepare a compound represented by the following Formula 4; 2) deprotecting the compound that is represented by the following Formula 4 and is prepared in step 1) using HCl-dioxane and chloroform to prepare a compound represented by the following Formula 5 ; and

3) performing reductive amination of the compound that is represented by the following Formula 5 and is prepared in step 2) with an aldehyde compound represented by the following Formula 6 to prepare the compound represented by Formula 1. The process is represented by the following Reaction Scheme 1. <Reaction Scheme 1>

_RH + H— BOC

4MHCl-dI«κane

/CBCl₃

R₈- (CH₂)_1T—N_H2

1 6 5 wherein Ri, R₂ and n are the same as defined in Formula 1.

The preparation method of the present invention will be described in detail as follows.

The amine compound of Formula 2 used in the preparation method is preferably benzylamine derivatives or aniline derivatives. The benzylamine derivatives include 1- ( (4-chlorophenyl) (phenyl) methyl) piperazine and

(4-chlorophenyl) (phenyl) methanamine, and the aniline derivatives include 4- (p-tolyloxy) benzeneamine and 2, 6-dimethylaniline.

The compound of Formula 3 is preferably amino acid where nitrogen is protected by a t-butyloxycarbonyl (BOC) group.

The aldehyde compound of Formula 6 is preferably acetaldehyde, cyclohexanecarboxaldehyde, 4- (dimethylamino) benzaldehyde, isobutyraldehyde, 2-ethylbutyraldehyde, benzaldehyde, 4-methoxybenzaldehyde, 4 -nitrobenzaldehyde,

4-isopropylbenzaldehyde or 2, β-dichlorobenzaldehyde .

In step 1) , the condensation reaction may be performed under the conventional conditions for peptide binding reactions, well known in the art. The reaction solvent used in the reaction includes ethyl ether, THF (tetrahydrofuran) , dichloromethane, chloroform, DMSO (dimethyl sulfonyloxide) , and DMF (dimethylformamide) , and preferably DMF. To facilitate the reaction, a coupling agent of peptide binding reactions known to those skilled in the art may be used as a catalyst in the presence or absence of a base such as TEA (triethylamine) , DIEA (N, N-diisopropylethylamine) and NMM (N-methyl morpholine) . Examples of the coupling agent include DIC (diisopropyl carbodiimide) , EDC

(1- (3-dimethylaminopropyl) -3-ethylcarbodiimide) , TBTU (2- (1-H-benzotriazol-l-yl) -1, 1, 3, 3-tetramethyluromium tetrafluoro borate) , DCC (dicyclohexyl carbodiimide) , HATU (dimethylamino- ( [l,2,3]triazolo[4,5-b] pyridin-3-yloxy) -methy lene) -dimethyl-ammonium hexafluorophosphate) , and- PyBOP (benzotriazol-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate) . In the present invention, PyBOP is preferably used as the reaction catalyst in the presence of DIEA.

In step 2) , the compound represented by Formula 4 is reacted with HCl-dioxane and chloroform to deprotect the t-butyloxycarbonyl (BOC) protecting group on nitrogen.

In step 3) , the reductive amination may be performed in an inactive solvent in the presence of a reducing agent . The reducing agent is not particularly limited, but preferably selected from sodium borohydride (NaBH₄) , sodium cyano borohydride (NaBH₃CN) and sodium triacetoxy borohydride (NaBH(OAc)₃), and most preferably sodium triacetoxy borohydride.

In addition, the present invention provides a pain relief composition, comprising the compound of Formula 1 or a pharmaceutically acceptable salt thereof.

The compound of the present invention has excellent inhibitory effect on T-type calcium channel activity, and chronic neuropathic and inflammatory pain, thereby being used to relieve pain. The composition of the present invention may include one or more known active ingredients having an inhibitory effect on pain, together with the compound of Formula 1.

For administration, the composition of the present invention may further include one or more pharmaceutically acceptable carriers, in addition to the above described active ingredients.

Pharmaceutically acceptable carriers may be saline solution, sterile water, Ringer's solution, buffered saline, dextrose solution, maltodextrin solution, glycerol, ethanol or a mixture of one or more thereof. If necessary, other common additives such as antioxidants, buffered solutions, and bacteriostatic agents may be used together. Moreover, the composition may additionally include diluents, dispersants, surfactants, binders, and lubricants in order to formulate it into injectable formulations such as aqueous solution, suspension, and emulsion, or pills, capsules, granules, and tablets. Furthermore, the composition may preferably be formulated depending on particular diseases and its components, using the method described in Remington's Pharmaceutical Science (latest edition), Mack Publishing Company, Easton PA, which is a suitable method in the relevant field of art.

The composition of the invention may be administered orally or parenterally (for example, intravein, subcutaneous, intraperitoneal, or topical application) , depending on the purpose. The dosage of the composition may vary depending on various factors, including the patient' s weight, age, sex, health condition, and diet. It may additionally vary depending on administration time, administration route, secretion rate, disease severity, etc. The compound of Formula 1 is administered at a daily dosage of about 5-250 mg/kg, preferably 8-60 mg/kg one time or several times.

The composition of the present invention may be used alone or in combination with surgical operations, hormone therapies, chemical therapies, and other methods using biological reaction regulators, in order to relieve pain. Hereinafter, the preferred Examples are provided for better understanding. However, these Examples are for illustrative purposes only, and the invention is not intended to be limited by these Examples.

[Mode for Invention]

A. Preparation of t-butyl-substituted carbamate

Preparation Example 1 : Preparation of t-butyl 4- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4-oxobu tylcarbamate

2.46 mmol of 4- (Boc-amino) butanoic acid, 2.71 mmol of 1- ( (4-chlorophenyl) (phenyl) methyl) piperazine, and 2.71 mmol of benzotriazol-1-yl-oxytris-pyrrolidinophosphonium hexafluorophosphate (PyBOP) were dissolved in 20 mL of dimethylformamide, and 4.92 mmol of N,N-diisopropylethylamine (DIEA) was added thereto, followed by stirring at room temperature for 16 hrs . 20 mL of 10% HCl was added to the reaction mixture and extracted with 30 mL of ethyl acetate (EtOAc) . An organic layer was washed with 20 mL of 10% HCl, and then washed with 20 mL of a saturated NaHCO₃ solution twice, and washed with 20 mL of a saturated NaCl solution twice. The organic layer was collected, and dried over anhydrous MgSO₄, followed by filtration under reduced pressure. The organic solvent was removed from filtrate under reduced pressure to give a desired compound (yield: 80%) .

¹H NMR (Acd₆) δ 7.42-7.5 (m, 4H) , 7.25-7.32 (m, 4H) , 7.2-7.22 (m, IH) , 6.0 (brs, IH) , 4.4 (s, IH) , 3.5-3.6 (m, 4H) , 3.1 (q, J=6.4 Hz, 2H) , 2.3-2.4 (m, 6H) , 1.7-1.8 (m, 2H) , 1.4 (s, 9H)

Preparation Example 2 : Preparation of t-butyl 3- (4- (p-tolyloxy)phenylcarbamoyl)propylcarbamate

A desired compound was prepared in the same manners as in Preparation Example 1, except using 4- (p-tolyloxy) benzeneamine instead of 1- ( (4-chlorophenyl) (phenyl) methyl) piperazine in Preparation Example 1 (yield : 42%) . 1H NMR (Acd₆)δ 9.4 (brs, IH), 7.7 (d, J=9.2 Hz, 2H), 7.2 (d, J=9.2 Hz, 2H), 6.9 (d, J=9.2 Hz, 2H), 6.85 (d, J=9.2 Hz, 2H), 6.0 (brs, IH), 3.15 (q, J=6.4 Hz, 2H), 2.4 (t, J=I .2 Hz, 2H), 2.3 (s, 3H), 1.8-1.84 (m, 2H), 1.4 (s, 9H)

Preparation Example 3 : Preparation of t-butyl 3- ( (4-chlorophenyl) (phenyl) methyl) carbamoyl) propylcarbamate

A desired compound was prepared in the same manners as in

Preparation Example 1, except using

(4-chlorophenyl) (phenyl) methanamine instead of 1- ( (4-chlorophenyl) (phenyl) methyl) piperazine in Preparation

Example 1 (yield : 51%) .

¹H NMR (Acd₆) δ 8.0 (brs, IH), 7.24-7.38 (m, 9H), 6.24 (d, J=8.4 Hz, IH), 6.0 (brs, IH), 3.1 (q, J=6.4 Hz, 2H), 2.32 (t, J=7.4 Hz, 2H), 1.74-1.82 (m, 2H), 1.4 (s, 9H)

Preparation Example 4 : Preparation of t-butyl 3- (2 , 6-dimethylphenylcarbamoyl) propylcarbamate A desired compound was prepared in the same manners as in Preparation Example 1, except using 2, β-dimethylaniline instead of 1- ( (4-chlorophenyl) (phenyl) methyl) piperazine in Preparation Example 1 (yield : 72%) . 1H NMR (Acd₆) δ 8.5 (brs, IH), 7.0 (s, 3H), 6.0 (brs, IH), 3.2 (q, J=β.6Hz, 2H), 2.4 (t, J=7.2Hz, 2H), 2.2 (s, 6H), 1.8-1.85 (m, 2H), 1.4 (s, 9H)

B. Preparation of 4-amino-N-substituted butanamide Preparation Example 5: Preparation of

4-amino-l- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one

0.76 mmol of t-butyl

4- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4-oxobu tylcarbamate prepared in Preparation Example 1 was added to chloroform (5 mL) and 4 M HCl-dioxane (5 mL) , and then stirred for 3 hrs . The solvent was removed under reduced pressure to give a desired compound (yield: 100%) .

¹H NMR (D₂O) δ 7.56-7.62 (m, 4H) , 7.4-7.54 (m, 5H) , 3.72-3.8 (m, 5H), 2.7-3.16 (m, 6H), 2.58 (t, J=7.4 Hz, 2H), 1.9-2.0 (m, 2H) ;

HR-FABMS Calcd for C_2IH₂₇ON₃Cl : (M⁺+l ) : 372 . 1843 , Found: 372 . 1838 Preparation Example 6 : Preparation of

4-amino-N- (4-p-tolyloxy) phenyl) butanamide

A desired compound was prepared in the same manners as in Preparation Example 5, except using t-butyl 3- (4- (p-tolyloxy) phenylcarbamoyl) propylcarbamate prepared in Preparation Example 2 instead of t-butyl 4- ( 4- ( ( 4-chlorophenyl ) (phenyl) methyl) piperazin-1-yl) -4-oxobu tylcarbamate in Preparation Example 5 (yield: 91%) .

¹H NMR (DMSO-de) δ 7.7 (brs, 3H), 7.55 (d, J=9.2 Hz, 2H), 7.15 (d, J=8.4 Hz, 2H), 6.9 (d, J=Q .8 Hz, 2H), 6.85 (d, J=8.4 Hz, 2H), 2.84 (t, J=7.8 Hz, 2H), 2.4 (t, J=I .2 Hz, 2H), 2.28 (s, 3H), 1.8-1.88 (m, 2H)

Preparation Example 7 : Preparation of

4-amino-N- ( (4-chlorophenyl) (phenyl) methyl) butanamide

A desired compound was prepared in the same manners as in Preparation Example 5, except using t-butyl 3- ( (4-chlorophenyl) (phenyl) methyl) carbamoyl) propylcarbamate prepared in Preparation Example 3 instead of t-butyl 4- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4-oxobu tylcarbamate in Preparation Example 5 (yield: 96%) .

¹H NMR (DMSO-de) δ 7.7 (brs, 3H), 7.2-7.4 (m, 9H), β.l(d, J=8.4 Hz, IH), 2.76 (t, J=I. Q Hz, 2H), 2.32 (t, J=I .2 Hz, 2H), 1.74-1.82 (m, 2H)

Preparation Example 8 : Preparation of

4-amino-N- (2 , 6-dimethylphenyl)butanamide

A desired compound was prepared in the same manners as in Preparation Example 5, except using t-butyl 3- (2, 6-dimethylphenylcarbamoyl) propylcarbamate prepared in Preparation Example 4 instead of t-butyl 4- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4-oxobu tylcarbamate in Preparation Example 5 (yield: 100%) .

¹H NMR (DMSO-d₆) 5 7.8 (brs, 3H) , 7.0 (s, 3H) , 2.85 (q, J=I .6 Hz, 2H), 2.44 (t, J=7.2 Hz, 2H), 2.1 (s, 6H), 1.84-1.9 (m, 2H)

C . Preparation of

4-substituted-l- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin -l-yl)butan-l-one

Example 1: Preparation of 1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (ethy lamino) butan-1-one

0.5 mmol of

4-amino-1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one prepared in Preparation Example 5 and acetaldehyde were dissolved in 1, 2-dichloroethane (9mL), and 0.7 mmol of sodium triacetoxy borohydride (NaBH(OAc)₃) and 0.5 mmol of triethylamine were added thereto. The mixture was reacted under nitrogen at room temperature overnight, and the reaction was terminated with a saturated NaHCO₃ solution. The reaction mixture was extracted with ethylacetate (EtOAc) , and then dried over MgSO₄, followed by filtration under reduced pressure. The organic solvent was removed from filtrate under reduced pressure to give a desired compound (yield: 79%) .

¹H NMR (CDCl₃) δ 7.34-7.38 (m, 4H) , 7.2-7.3 (m, 5H) , 4.2 (s, IH), 3.58-3.63 (m, 2H), 3.44-3.48 (m, 2H), 2.65 (q, J=6.8 Hz, 2H) , 2.44-2.56 (m, 2H) , 2.3-2.4 (m, 6H) , 1.74-1.82 (m, 2H) , 1.0-1.1 (m, 3H)

Example 2 :

Preparation of

1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (cycl ohexylmethylamino)butan-1-one

A desired compound was prepared in the same manners as in Example 1, except using cyclohexanecarboxaldehyde instead of acetaldehyde in Example 1 (yield: 20%) .

¹H NMR (CDCl₃) 5 7.34-7.38 (m, 4H), 7.2-7.3 (m, 5H), 4.2 (s,

IH), 3.58-3.62 (m, 2H), 3.44-3.48 (m, 2H), 2.74-2.8 (t, J=6.8

Hz, 2H) , 2.5-2.54 (d, J=6.4 Hz, 2H) , 2.42 (t, J=7.0Hz, 2H) , 2.3-2.4

(m, 4H), 1.84-1.9 (m, 2H), 1.62-1.8 (m, 4H), l.l-1.3(m, 4H), 0.84-0.96 (m, 3H);

HR-FABMS Calcd for C₂₈H₃₇ON₃Cl : (M⁺+l ) : 468 . 2782 , Found : 468 . 2778 .

Example 3 : Preparation of 4- (4- (dimethylamino) benzylamino) -1- (4- ( (4-chlorophenyl) (phen yl) methyl) piperazin-l-yl) butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using 4- (dimethylamino) benzaldehyde instead of acetaldehyde in Example 1 (yield: 33%) .

¹HNMR (Acd₆) 5 7.45-7.7 (m, 5H), 7.15-7.35 (m, 5H), 6.7-6.8 (m, 3H), 4.3 (s, IH), 3.5-3.58 (m, 6H), 3.0 (s, 6H), 2.88-2.9 (m, 2H) , 2.38 (t, J=7.4 Hz, 2H) , 2.3-2.36 (m, 4H) , 1.86-1.93 (m, 2H)

Example 4 : Preparation of 1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (isob utylamino) butan-1-one

A desired compound was prepared in the same manners as in Example 1, except using isobutyraldehyde instead of acetaldehyde in Example 1 (yield: 43%) .

¹H NMR (CDCl₃) 5 7.34-7.38 (m, 4H) , 7.2-7.3 (m, 5H) , 4.2 (s, IH) , 3.58-3.64 (m, 2H) , 3.44-3.48 (m, 2H) , 2.62-2.66 (t, J=6.8 Hz, 2H) , 2.3-2.42 (m, 6H) , 1.7-1.84 (m, 4H) , 1.24-1.28 (t, J=I .2 Hz, IH) , 0.88-0.92 (d, J=6.8 Hz, 6H)

Example 5 : Preparation of

4- (2-ethylbutylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) p iperazin-1-yl) butan-1-one

A desired compound was prepared in the same manners as in Example 1, except using 2-ethylbutyraldehyde instead of acetaldehyde in Example 1 (yield: 25%) .

¹H NMR (CDCl₃) 5 7.34-7.4 (m, 4H) , 7.2-7.3 (m, 5H) , 4.2 (m, IH) , 3.4-3.66 (m, 6H) , 2.3-2.4 (m, 6H) , 1.88-2.0 (m, 2H) , 1.8-1.82 (m, IH) , 1.6-1.7 (m, 4H) , 1.4-1.5 (m, 2H) , 0.78-0.96 (m, 6H)

Example 6 : Preparation of

4- (benzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperaz in-l-γl)butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using benzaldehyde instead of acetaldehyde in Example 1 (yield: 3%) .

¹H NMR (CDCl₃) 5 7.2-7.4 (m, 14H) , 4.2 (s, IH) , 3.9 (s, 2H) , 3.56-3.62 (m, 2H), 3.42-3.46 (m, 2H), 2.8 (t, J=6.4 Hz, 2H), 2.4 (t, J=6.8 Hz, 2H), 2.3-2.38 (m, 4H), 1.88-1.94 (m, 2H)

Example 7 : Preparation of

4- (4-methoxybenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methy l)piperazin-l-yl)butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using 4-methoxybenzaldehyde instead of acetaldehyde in Example 1 (yield: 19%) .

¹H NMR (CDCl₃) δ 7.2-7.38 (m, HH), 6.84-6.9 (m, 2H), 4.2 (s, IH), 3.9 (s, 2H), 3.8 (s, 3H), 3.55-3.6 (m, 2H), 3.4-3.5 (m, 2H), 2.8 (m, 2H), 2.3-2.5 (m, 6H), 1.9-2.0 (m, 2H)

Example 8 : Preparation of

4- (4-nitrobenzylami.no) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-l-yl)butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using 4-nitrobenzaldehyde instead of acetaldehyde in Example 1 (yield: 76%) .

¹H NMR (CDCl₃) δ 8.24 (d, J=8.8 Hz, IH), 8.16 (d, J=S .8 Hz, IH), 7.55 (d, J=8.4 Hz, IH), 7.5 (d, J=8.4 Hz, IH), 7.2-7.4 (m, 9H), 4.2 (s, IH), 3.9 (s, 2H), 3.6-3.65 (m, 2H), 3.4-3.5 (m, 2H), 2.6 (t, J=6.8 Hz, 2H) 2.3-2.4 (m, 6H), 1.8-1.88 (m, 2H)

Example 9 : Preparation of

4- (4-isopropylbenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) met hyl) piperazin-l-yl) butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using 4-isopropylbenzaldehyde instead of acetaldehyde in Example 1 (yield: 7%) .

¹H NMR (CDCl₃) δ 7.6 (d, J=8.0 Hz, IH), 7.2-7.4 (m, HH) , 7.18 (d, J=8.0Hz, IH) 4.2 (d, J=6.4Hz, IH), 3.74 (s, 2H), 3.58-3.64 (m, 2H), 3.44-3.48 (m, 2H), 2.86-2.96 (m, IH), 2.68 (t, J=6.8 Hz, 2H), 2.3-2.4 (m, 6H), 1.98-2.04 (m, 2H), 1.2-1.3 (m, 6H)

Example 1£ : Preparation of

4- (2 , 6-dichlorobenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) me thyl)piperazin-l-yl)butan-l-one

A desired compound was prepared in the same manners as in Example 1, except using 2, 6-dichlorobenzaldehyde instead of acetaldehyde in Example 1 (yield: 25%) .

¹H NMR (CDCl₃) 5 7.2-7.38 (m, 12H), 4.2 (s, IH), 3.74-3.78 (m, 2H), 3.58-3.64 (m, 2H), 3.44-3.5 (m, 2H), 2.44 (t, J=7.6 Hz, 2H), 2.3-2.4 (m, 4H), 2.04-2.12 (m, 2H), 1.8-1.84 (m, 2H)

Experimental Example 1: Measurement of T-type calcium channel activity using whole-cell patch-clamp technique

DMEM (Dulbecco' s modified Eagle' s medium) supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (v/v) was used as a culture medium. Cells were cultured at 3β.5^°C in a humidified incubator (95% O₂/ 5% CO₂) . The culture solution was replaced with a fresh medium every 3 to 4 days and the cultured cells were subjected to subculture every week. At this time, the culture solution was treated with a G-418 (0.5 mg/ml) solution so that only HEK 293 cells expressing αi_G T-type calcium channel can grow. The cells used for the T-type calcium channel activity assay were cultured on a cover slip coated with poly-L-lysine (0.5 mg/ml) whenever sub-cultured and their calcium channel activity was recorded 2 to 4 days after the cultivation. The current of the T-type calcium channel at a single cell level was measured according to an electrophysiological whole cell patch clamping method using an EPC-9 amplifier (HEKA, German) . At this time, a cell exterior solution [140 mM NaCl, 2 mM CaCl₂, 10 mM HEPES (pH 7.4)] and a cell interior solution [KCl 130 mM, HEPES 10 mM, EGTA 11 mM, MgATP 5 mM (pH 7.4) ] were employed. The inward current caused by the T-type calcium channel activation was measured according to a T-type calcium channel protocol activated at low current . Such current occured when the cells were converted into a whole-cell recordingmode by stabbing amicroglass electrode having 3-4 MΩ resistance, which was filled with the cell interior solution, into a single cell and depolarized at -30 mV (50 ms duration period) every 15 seconds with fixing membrane potential to -100 mV. The results are shown in Table 1.

[Table 1]

As shown in Table 1, it was found that the compound according to the present invention effectively inhibited the T-type calcium channel activity.

Experimental Example 2 : Pain-relieving effect of the compound of the present invention on chronic neuropathic pain

The following experiment was performed to confirm the inhibitory effect of the compound of the present invention on chronic neuropathic pain.

1. Induction of chronic neuropathic pain - Preparation of tail nerve injury model

Eight-week-old sprague-Dawley rats were freely bred by providing enough feed and water, while maintaining 22-25 ^°C and a 12-hour interval light-dark cycle (providing a light into the cages from 7 a.m.) .

To induce chronic neuropathic pain, the rats were anesthetized with 0.5-2% enflurane, and then the inferior/superior caudal trunks distributed at their tails were cut between the Sl and S2 spinal nerves. To prevent reconnection of the proximal and distal ends of the severed trunk, the proximal end of the trunk was cut more by about 1 mm. The prepared test subjects feel chronic neuropathic pain, since their Sl spinal nerves controlling nerves around the tail are injured.

2. Measurement: of inhibitory effect on chronic neuropathic pain - mechanical , cold and warm allodynia tests

To examine chronic neuropathic pain in the tails (mechanical, cold and warm allodynia tests) , the behavioral tests were carried out 1 day before the surgery, and 1, 7 and 14 day(s) after the nerve surgery. To give mechanical, cold, and warm stimuli to the tails, the subject rats were restrained in a transparent plastic tube (4.5^χl2, 5.5^χ5, 6.5><18 cm: diameter * length) . Prior to the behavioral tests, the subject rats were adapted to the test environment for 1 hr. At the 14 day mark after the nerve surgery, the compounds (60 mg/kg) prepared in Preparation Example 5 and Example 2 were intraperitoneally injected to each of the subject rats. The behavioral tests were conductedat 1, 3 and 5 hrs after the injection, so as to measure the anti-allodynia effect of the present compound. At this time, a solvent/vehicle was used as a control group.

1) Mechanical allodynia test To assess mechanical sensitivity at the tails of the subject rats, the withdrawal threshold was measured by using the up-down method. By using a set of von Frey filaments (0.4, 0.6, 1.0, 2.0, 4.0, 6.0, 8.0, 15.0 g, Stoelting, Wood Dale, IL, USA), a brisk tail flick to von Frey application was regarded as a withdrawal response. The first stimulus was made by a 2.0 g filament. When there was a withdrawal response, the next weaker filament was used. When no response was shown, the next stronger filament was administered. Interpolation was carried out to 50% threshold according to the Dixon method. 2) Cold and warm allodynia tests

To confirm the cold and warm allodynia-relieving effects of the compound according to the present invention, withdrawal latency was measured to assess cold and warm sensitivity in the following methods. Withdrawal latency was measured by a time to showwithdrawal response after immersing the tails of the subject rats in cold (4^°C) and warm (40^°C) water baths. If the response was not shown till 15 sec, 15 sec was recorded as the result. This test was repeated five times at intervals of 5 min, and the results were averaged. As a result, it was confirmed that as the response time is shorter, cold and warmallodynia of the subject rats is more severe.

The inhibitory effects of the compositions of Preparation Example 5 and Example 2 on chronic neuropathic pain are shown in FIGs. 1 and 2 (A: mechanical allodynia, B: cold allodynia, C: warm allodynia) . In FIGs. 1 and 2, the vertical dotted line indicates the time of injection, and the n value determines the number of rats used in the experiment.

The compound of the present invention showed excellent inhibitory effects on chronic neuropathic pain, as compared to the solvent control group, as shown in FIGs . 1 and 2. The compound of the present invention showed a significant level of pain relieving effect to a stimulus causing mechanical allodynia, cold allodynia, and warm allodynia at 1 hr after the injection (P<0.05) .

Experimental Example 3 : Pain-relieving effect of the compound of the present invention on inflammatory pain To confirm the pain-relieving effect of the composition of the present invention on inflammatory pain, a test was conducted by using formalin that is an inflammation-inducing material, as follows .

Formalin (5%, 50 βl) and compounds prepared in Preparation Example 5 and Examples 1 to 3 ( 60 /zg/kg) were injected subcutaneously into the dorsal surfaces of one-side hind paws of the subject rats. Formalin (5%, 50 μi) was injected subcutaneously into the dorsal surfaces of one-side hind paws of the control group. Then, the subject rats were placed into an observation chamber (16 x 14 cm each) to observe licking and biting their paws at intervals of 5 min for 60 min. Phase I was defined as the first 10 min after the formalin injection, phase II was the following 50 min, and then the results were analyzed.

The pain-relieving effects of the compounds of Preparation Example 5 and Examples 1 to 3 on inflammatory pain are shown in FIGs. 3 to 6, respectively. The compounds of the present invention showed a superior pain-relieving effect to the control group in Phase I and II, as shown in FIGs 3 to 6.

Hereinbelow, Formulation Examples for the composition of the present invention will be illustrated.

Formulation Example 1 : Preparation of liquid injectable formulation

An injectable liquid formulation containing 10 mg of the active ingredient was prepared by the following method. 1 g of the compound of Formula 1, 0.6 g of sodium chloride, and 0.1 g of ascorbic acid were dissolved in distilled water to be 100 ml. The solution was put into a bottle, and heated to be sterilized at 20^°C for 30 minutes.

The composition of the injectable liquid formulation is as follows.

Compound of Formula 1 I g

Sodium chloride 0.6 g

Ascorbic acid 0.1 g

Distilled water predetermined amount

Formulation Example 2 : Preparation of syrup formulation A syrup formulation containing the compound of Formula 1 as an active ingredient (2%, weight/volume) was prepared by the following method.

The compound of Formula 1, saccharin, and sugar were dissolved in 80 g of warm water. The solution was cooled, and a solution containing glycerin, saccharin, flavor, ethanol, sorbic acid, and distilled water was added thereto. Water was added to the mixture to be 100 ml.

The composition of the syrup formulation is as follows. Compound of Formula 1 2 g Saccharin 0.8 g

Sugar 25.4 g

Glycerin 8.O g

Flavor 0.04 g

Ethanol 4.O g Sorbic acid 0.4 g

Distilled water predetermined amount

Formulation Example 3 : Preparation of tablet formulation

A tablet formulation containing 15 mg of the active ingredient was prepared as the following method.

250 g of the compound of Formula 1 was mixed with 175.9 g of lactose, 180 g of starch, and 32 g of colloidal silicic acid. 10% Gelatin solution was added to the mixture, and then pulverized to pass through a 14-mesh sieve. The mixture was dried. Then, 160 g of starch, 50 g of talc, and 5 g of magnesium stearate were added thereto to prepare a tablet.

The composition of the tablet formulation is as follows. Compound of Formula 1 250 g Lactose 175 . 9 g Starch 180 g

Colloidal silicic acid 32 g 10% Gelatin solution Starch 160 g Talc 50 g Magnesium stearate 5 g

[industrial Applicability]

The compound of the present invention has excellent inhibitory effect on T-type calcium channel activity, and chronic neuropathic and inflammatory pain, thereby being used to relieve pain.

Claims

[CLAIMS]

[Claim 1]

A compound represented by the following Formula 1: <Formula 1>

wherein Ri is hydrogen; straight or branched Ci-Ci₀ alkyl; CH₂-C₃-Ci₀ cycloalkyl; or benzyl substituted or unsubstituted with one or more groups selected from the group consisting of straight or branched Ci~Cio alkyl, Ci-C₄ alkoxy, halogen, nitro and N (CH₃) ₂,

R₃ and R₄ are each independently C₆-C₂₀ aryl or halogen-substituted C₆-C₂₀ aryl,

R₅ and R₆ are each independently hydrogen; C₆-C_2O aryl substituted with one or more groups selected from p-tolyloxy and Ci-C₄ alkyl; or CH(C₆-C₂₀ aryl) (halogen-substituted C₆-C₂₀ aryl), and n is an integer of 1 to 5.

[Claim 2]

The compound according to claim 1, wherein Ri is hydrogen; ethyl; isobutyl; 2-ethylbutyl; CH₂-cyclohexyl; or benzyl substituted or unsubstituted with one or more groups selected from the group consisting of isopropyl, methoxy, Cl, nitro and

N(CH₃)₂, CH-N N«ΛΛΛ

R₂ is or NR₅R₆,

R₃ and R₄ are each independently phenyl or 4-chlorophenyl,

R₅ and R₆ are each independently hydrogen, (p-tolyloxy) -phenyl, CH (phenyl) (4-chlorophenyl) , or 2, β-dimethylphenyl, and n is an integer of 3.

[Claim 3]

The compound according to claim 1, wherein the compound is selected from the group consisting of 1)

4 -amino- 1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one,

2 ) 4-amino-N- (4-p-tolyloxy) phenyl) butanamide,

3) 4-amino-N- ( (4-chlorophenyl) (phenyl) methyl) butanamide, 4) 4-amino-N- (2, β-dimethylphenyl) butanamide,

5)

1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (ethy lamino) butan-1-one,

6) 1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (cycl ohexylmethylamino) butan-1-one,

7)

4- (4- (dimethylamino) benzylamino) -1- (4- ( (4-chlorophenyl) (phen yl) methyl) piperazin-1-yl) butan-1-one, 8) 1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) -4- (isob utylamino) butan-1-one,

9)

4- (2-ethylbutylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) p iperazin-1-yl) butan-1-one,

10)

4- (benzylamino) -1- (4- ( (4-chlorophenyl) (phenyl ) methyl ) piperaz in-l-yl) butan-1-one,

H) 4- (4-methoxybenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methy 1) piperazin-1-yl) butan-1-one,

12)

4- (4-nitrobenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl) methyl) piperazin-1-yl) butan-1-one, 13)

14)

4- (2, 6-dichlorobenzylamino) -1- (4- ( (4-chlorophenyl) (phenyl)me thyl) piperazin-1-yl) butan-1-one . [Claim 4]

A process for preparing the compound of claim 1, comprising the steps of

1) performing a condensation reaction of an amine compound represented by the following Formula 2 and a compound represented by the following Formula 3 to prepare a compound represented by the following Formula 4; 2) deprotecting the compound that is represented by the following Formula 4 and is prepared in step 1) using HCl-dioxane and chloroform to prepare a compound represented by the following Formula 5; and 3) performing reductive amination of the compound that is represented by the following Formula 5 and is prepared in step 2) with an aldehyde compound represented by the following Formula 6 to prepare a compound represented by Formula 1. The process is represented by the following Reaction Scheme 1. <Reaction Scheme 1>

O O

_{RiH + H0}__c_fcH₂)- f1 BOC *» _R2 c (OH,)- [J—_BOC

PyBOP ^{v /n}

3 4

4MHCl-dioxane

/CHCk

1 6 ₅ wherein Ri is hydrogen; straight or branched Ci~Cio alkyl;

CH₂-C₃~Cio cycloalkyl; or benzyl substituted or unsubstituted with one or more groups selected from the group consisting of straight or branched Ci~Cio alkyl, Ci~C₄ alkoxy, halogen, nitro and N (CH₃) ₂,

\

CH--N NiΛΛΛ

R₂ is or NR₅R₆, R₃ and R₄ are each independently C₆-C_2O aryl or halogen-substituted C₆~C2o aryl,

R₅ and R₆ are each independently hydrogen; C₆-C₂O aryl substituted with one or more groups selected from p-tolyloxy and Ci-C₄ alkyl; or CH(C₆-C₂₀ aryl) (halogen-substituted C₆-C₂O aryl), and n is an integer of 1 to 5.

[Claim 5]

A pain relief composition, comprising the compound of claim 1 or a pharmaceutically acceptable salt thereof.

[Claim 6]

The pain relief composition according to claim 5, wherein the pain is chronic neuropathic pain or inflammatory pain.