Field of the Invention:
The present invention provides an improved process for the preparation of 5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl][(lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1, represented by the following structural formula:
The present invention also relates to acid addition salts of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of general formula-4, represented by the following structural formula:
Background of the Invention:
5-[[[(2S)-2-Amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl][(lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid known as Eluxadoline and is approved in US under the brand name VTBERZI. Eluxadoline is a mu-opioid receptor agonist; eluxadoline is also a delta opioid receptor antagonist and a kappa opioid receptor agonist. The binding affinities (Ki) of eluxadoline for the human mu and delta opioid receptors are 1.8 nM and 430 nM, respectively. The binding affinity (Ki) of eluxadoline for the human kappa opioid receptor has not been determined; however, the Ki for guinea pig cerebellum kappa opioid receptor is 55 nM. In animals, eluxadoline interacts with opioid receptors in the gut.

5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl][(lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid and process for its preparation was first disclosed in US7741356 B2 herein after referred as US'356 B2.
Brief description of the Invention:
The first aspect of the present invention is to provide the acid addition salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of general formula-4 and process for its preparation.
The second aspect of the present invention is to provide the novel crystalline (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt compound of formula-4a, herein after designated as form-M and process for its preparation.
The third aspect of the present invention is to provide the novel crystalline (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt compound of formula-4b, herein after designated as form-S and process for its preparation.
The fourth aspect of the present invention relates to novel intermediate compounds useful in the preparation of compound of formula-1.
The fifth aspect of the present invention is to provide the novel process for the preparation of 5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl] [(1 S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1.
The sixth aspect of the present invention is to provide improved process for the preparation of 5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl] [(1 S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1.
Brief description of the Drawings:

Figure 1: Illustrates the PXRD pattern of crystalline form-M of maleate salt of (S)-methyl-2-
methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of
formula-4a.
Figure-2: Illustrates the PXRD pattern of crystalline form-S of oxalate salt of (S)-methyl-2-
methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of
formula-4b.
Detailed description of the Invention:
The first aspect of the present invention relates to novel crystalline form-M of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt compound of formula-4a characterized by its X-ray powder diffractogram having peaks at 8.1, 8.7, 9.6, 12.0, 15.2, 15.9, 17.6, 18.1, 18.6, 19.4, 19.6, 21.7, 22.5, 24.2, 24.9, 25.8, 26.4, 27.2, 28.7, 31.6 and 34.4 ± 0.2 degrees two-theta as illustrated in figure-1.
The second aspect of the present invention relates to novel crystalline form-S of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt compound of formula-4b characterized by its X-ray powder diffractogram as illustrated in figure-2.
The third aspect of the present invention relates to acid addition salts of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of general formula-4 and process for their preparation, which comprises of reacting the compound of formula-4 with a suitable acid in a suitable solvent to provide acid addition salts of compound of general formula-4.
Wherein, the acid is selected from inorganic acids, such as hydrobromic acid, hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid; and organic acids such as oxalic acid, maleic acid, malonic acid, tartaric acid, fumaric acid, citric acid, malic acid, succinic acid, mandelic acid, lactic acid, acetic acid, propionic acid, 2-chloromandelate, p-toluene sulfonic acid, ethane-l,2-disulfonic acid, camphor sulfonic acid, ethane sulfonic acid, methane sulfonic acid, naphthalene-2-sulfonic acid, benzene sulfonic acid, adipic acid, glutaric acid, glutamic acid, palmitic acid or aspartic acid;

The suitable solvent used in the present invention is selected from "hydrocarbon solvents" such as n-hexane, n-heptane, cyclohexane, pet ether, toluene, pentane, cycloheptane, methyl cyclohexane, m-, o-, or p-xylene, and the like; "ether solvents" such as dimethoxy methane, tetrahydrofuran, 1,3-dioxane, 1,4-dioxane, furan, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, anisole, t-butyl methyl ether, 1,2-dimethoxy ethane and the like; "ester solvents" such as methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate and the like; "polar-aprotic solvents such as dimethylacetamide (DMA), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) and the like; "chloro solvents" such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and the like; "ketone solvents" such as acetone, methyl ethyl ketone, methyl isobutylketone and the like; "nitrile solvents" such as acetonitrile, propionitrile, isobutyronitrile and the like; "alcoholic solvents" such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, 2-nitroethanol, 2-fluoroethanol, 2,2,2-trifluoroethanol, ethylene glycol, 2-methoxyethanol, 1, 2-ethoxyethanol, diethylene glycol, 1, 2, or 3-pentanol, neo-pentyl alcohol, t-pentyl alcohol, diethylene glycol monoethyl ether, cyclohexanol, benzyl alcohol, phenol, or glycerol and the like; "polar solvents" such as water or mixtures thereof.
The preferred embodiment of the present invention provides a process for the preparation of crystalline form-M of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt compound of formula-4a comprising of the following steps:
a. Adding isopropanol to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)
ethyl)amino)methyl)benzoate compound of formula-4,
b. adding maleic acid to the reaction mixture,
c. stirring the reaction mixture at 25-30°C,
d. filtering the precipitated solid to get the crystalline form-M of (S)-methyl-2-methoxy-
5-(((l -(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt
compound of formula-4a.

The preferred embodiment of the present invention provides a process for the preparation of crystalline form-S of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt compound of formula-4b comprising of the following steps:
a. Adding isopropanol to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)
ethyl)amino)methyl)benzoate compound of formula-4,
b. adding oxalic acid to the reaction mixture,
c. stirring the reaction mixture at 25-30°C,
d. filtering the precipitated solid to get the crystalline form-S of (S)-methyl-2-methoxy-
5-(((l -(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt
compound of formula-4b.
Further the acid addition salts of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of general formula-4 can be converted in to highly pure (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino) methyl)benzoate compound of formula-4, by treating acid addition salts of compound of general formula-4 with a suitable base.
According to the prior known process, (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4 is obtained as residue with low yield and high impurities.
Utilizing such a low quality compound of formula-4 with carry over impurities leads to decrease the yield and purity of final compound of formula-1.
In order to reduce the level of the impurities, it is necessary to carry out a number of purifications at this stage. Generally, purification leads to loss of material, generation of lot of spent solvents and solid waste which are difficult to dispose which may lead to the pollution of the environment. Further, the said process increases the cost of the production and which is not recommended for commercial scale-up.
In order to overcome the aforementioned problems, inventors of the present invention have surprisingly found that the conversion of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-

imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4 into its acid addition salts compound of general formula-4 and then conversion of the acid addition salts of compound of general formula-4 into free base by treating with a suitable base to provide pure (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4 with high purity.
As a result, the present inventors have found that an acid addition salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4 can be prepared in high yield and high purity. Furthermore, the acid addition salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4 is obtained as a solid.
The fourth aspect of the present invention provide an improved process for the preparation of 5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl] [(1 S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1. The process of the present invention is schematically represented as below:

The fifth aspect of the present invention provides novel process for the preparation of 5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl][(lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1. The process of the present invention is schematically represented as below:

The sixth aspect of the present invention provides novel intermediate compounds represented by the following structural formula:

The novel compounds of formula-6, 7, 8 and 9 are useful in the preparation of compound of formula-1.
5-[[[(2S)-2-amino-3-[4-(aminocarbonyl)-2,6-dimethylphenyl]-l-oxopropyl][(lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl]amino]methyl]-2-methoxybenzoic acid compound of formula-1 produced by the present invention can be further micronized or milled in a conventional techniques to get the desired particle size to achieve desired solubility profile based on different forms of pharmaceutical composition requirements. Techniques that may be used for particle size reduction include, but not limited to ball, roller and hammer mills, and jet mills. Milling or micronization may be performed before drying, or after the completion of drying of the product.
The invention also encompasses pharmaceutical compositions comprising compound of formula-1 or salts thereof of the present invention. As used herein, the term "pharmaceutical compositions" or "pharmaceutical formulations" include tablets, pills, powders, liquids, suspensions, emulsions, granules, capsules, suppositories, or injection preparations. P-XRD Method of Analysis:
PXRD analysis of compounds produced by the present invention were carried out using BRUKER D8 ADVANCE/AXS X-Ray diffractometer using Cu Ka radiation of wavelength 1.5406 A° and continuous scan speed of 0.03°/min.
The process described in the present invention was demonstrated in examples illustrated below. These examples are provided as illustration only and therefore should not be construed as limitation of the scope of the invention.

Preparation of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino) methyl)benzoate: (Formula-4)
(S)-l-(4-phenyl-lH-imidazol-2-yl)ethanamine (48.2 gms) was added to a mixture of methyl-5-formyl-2-methoxybenzoate (50 gms) and methanol (300 ml) at 25-30°C and stirred for 2 hours at the same temperature. Cooled the reaction mixture to 0-5°C. Sodium borohydride (12.6 gms) was added to the reaction mixture at 0-5°C and stirred for 4 hours at the same temperature. Water (250 ml) was slowly added to the reaction mixture at 0-5°C. pH of reaction mixture was adjusted to 2.0 using aqueous hydrochloric acid solution (75 ml) at 0-5°C. Ethyl acetate (250 ml) was added to the reaction mixture at 0-5°C. Basified the reaction mixture using 10% sodium hydroxide solution at 0-5°C. Raised the reaction temperature to 25-30°C and stirred for 30 minutes at the same temperature. Both the organic and aqueous layers were separated and aqueous layer was extracted with ethyl acetate. Combine the organic layer and washed with aqueous sodium chloride solution. Distilled off the solvent completely from the organic layer under reduced pressure. Isopropanol (250 ml) was added to the obtained residue at 25-30°C and stirred for 10 minutes at the same temperature. Distilled off the solvent completely from the reaction mixture under reduced pressure to get the title compound. Yield: 93.2 gms; Purity by HPLC: 91.16%.
Example-2:
Preparation of maleate salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)
ethyl)amino)methyl)benzoate: (Formula-4a)
Isopropanol (400 ml) was added to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate (93.2 gms) at 25-30°C and stirred for 10 minutes at the same temperature. Maleic acid (29.8 gms) was added to the reaction mixture at 25-30°C and stirred for 2 hours at the same temperature. Filtered the precipitated solid, washed with isopropanol and dried to get the title compound. Yield: 105 gms; M.R: 154-158°C; Purity by HPLC: 97.49%. The P-XRD pattern of the obtained compound is depicted in figure-1.

Preparation of oxalate salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl) ethyl)amino)methyl)benzoate: (Formula-4b)
Isopropanol (400 ml) was added to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate (93.2 gms) at 25-30°C and stirred for 10 minutes at the same temperature. Oxalic acid (23.2 gms) was added to the reaction mixture at 25-30°C and stirred for 2 hours at the same temperature. Filtered the precipitated solid, washed with isopropanol and dried to get the title compound. Yield: 106 gms; M.R: 160-163°C. Purity by HPLC: 98.32 %. The P-XRD pattern of the obtained compound is depicted in figure-2.
Example-4:
Preparation of methyl-5-(((S)-2-((tertiarybutoxycarbonyl)amino)-3-(4-carbamoyl-2,6-
dimethylphenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido)methyl)-2-
methoxybenzoate:
Acetonitrile (125 ml) was added to (S)-2-((tertiarybutoxycarbonyl)amino)-3-(4-carbamoyl-2,6-dimethylphenyl)propanoic acid (25 gms) at 25-30°C and stirred for 10 minutes at the same temperature. Cooled the reaction mixture to 10-15°C. Hydroxy benzotriazole (5.0 gms), N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (14.2 gms) and (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate (35.7 gms) were added to the reaction mixture at 10-15°C and stirred for 5 minutes at the same temperature. Diisopropylethylamine (19.2 gms) was slowly added to the reaction mixture at 10-15°C. Raised the temperature of the reaction mixture to 25-30°C and stirred for 90 minutes at the same temperature. N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (7.1 gms) was added to the reaction mixture at 25-30°C and stirred for 1 hour at the same temperature. Water and ethyl acetate were added to the reaction mixture at 25-30°C and stirred for 20 minutes at the same temperature. Both the organic and aqueous layers were separated and aqueous layer was extracted with ethyl acetate at 25-30°C. Both the organic layers were washed twice with aqueous sodium carbonate solution followed by aqueous hydrochloric acid solution at 25-30°C. Organic layer was washed with aqueous sodium chloride solution at 25-30°C and distilled off the solvent completely from the organic

layer under reduced pressure. Cyclohexane (118.75 ml) was added to the obtained compound at 25-30°C and stirred for 1 hour at the same temperature. Filtered the precipitated solid, washed with cyclohexane and dried to get the title compound. Yield: 45 gms; M.R: 125-130°C; Purity by HPLC: 98.9 %.
Example-5:
Preparation of 5-(((S)-2-((tert-butoxycarbonyl)amino)-3-(4-carbamoyl-2,6-dimethyl
phenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido)methyl)-2-methoxy
benzoate lithium salt:
Aqueous lithium hydroxide solution was slowly added to a mixture of methyl-5-(((S)-2-((tert-butoxycarbonyl)amino)-3-(4-carbamoyl-2,6-dimethylphenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido)methyl)-2-methoxybenzoate (172.8 gms) and isopropanol (864 ml) at 0-5°C. Raised the reaction mixture temperature to 25-30°C and stirred for 12 hours at the same temperature. Heated the reaction mixture to 40-45°C and stirred for 3 hours at the same temperature. Cooled the reaction mixture to 25-30°C. Isopropanol (4150 ml) was added to the reaction mixture at 25-30°C and stirred for 45 minutes at the same temperature. Filtered the precipitated solid, washed with isopropanol and dried to get the title compound. Yield: 145.0 gms; Purity by HPLC: 99.45%;
Boc alcohol impurity: 0.13%; Boc diacid impurity: 0.13%; Boc isopropyl ester impurity: 0.18%; Boc ester impurity: 0.01%; Acid impurity: 0.01%; SMUI: 0.13%.
Example-6:
Preparation of 5-(((2S)-2-((tert-butoxycarbonyl)amino)-3-(4-carbamoyl-2,6-dimethyl
phenyl)-N-((lS)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido)methyl)-2-methoxy
benzoate sodium salt:
Tetrahydrofuran (870 ml) and water (435 ml) was added to 5-(((S)-2-((tert-butoxy carbonyl)amino)-3-(4-carbamoyl-2,6-dimethylphenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl) ethyl)propanamido)methyl)-2-methoxybenzoate lithium salt (145 gms) at 25-30°C. Sodium carbonate (27.3 gms) was added to the reaction mixture at 25-30°C. Heated the reaction mixture to 40-45°C and stirred for 45 minutes at the same temperature. Cooled the reaction mixture to 25-30°C. Isopropanol (2175 ml) was added to the reaction mixture at 25-30°C and

stirred for 3 hours at the same temperature. Filtered the precipitated solid, washed with tetrahydrofuran. To the obtained solid, tetrahydrofuran (840 ml) and water (420 ml) was added at 25-30°C. Heated the reaction mixture to 40-45°C and stirred for 45 minutes at the same temperature. Cooled the reaction mixture to 25-30°C. Isopropanol was added to the reaction mixture at 25-30°C and stirred for 3 hours at the same temperature. Filtered the precipitated solid, washed with tetrahydrofuran and dried to get the title compound. Yield: 130 gms; Purity by HPLC: 99.84%;
Boc alcohol impurity: 0.02%; Boc diacid impurity: 0.03%; Boc isopropyl ester impurity: 0.01%; Boc ester impurity: Not detected; Acid impurity: Not detected%; SMUI: 0.1%.
Example-7:
Preparation of crystalline form-M of Eluxadoline 2-butanol solvate:
Acetonitrile (200 ml) was added to 5-(((S)-2-((tert-butoxycarbonyl)amino)-3-(4-carbamoyl-2,6-dimethylphenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido) methyl)-2-methoxy benzoate sodium salt (100 gms) at 25-30°C. Cooled the reaction mixture to 0-5°C. Acetonitrile (100 ml) and hydrochloric acid solution was slowly added to the reaction mixture at 0-5°C. Raised the temperature of the reaction mixture to 20-25°C and stirred for 4 hours at the same temperature. Water was added to the reaction mixture at 20-25°C. Cooled the reaction mixture to 0-5°C. Neutralizing the reaction mixture using triethyl amine at 0-5°C. 2-Butanol (3000 ml) was added to the reaction mixture at 0-5°C. Raised the temperature of the reaction mixture to 25-30°C and stirred for 6 hours at the same temperature. Cooled the reaction mixture to 0-5°C and stirred for 2 hours at the same temperature. Filtered the precipitated solid, washed with 2-butanol and dried to get the title compound.
Yield: 76.5 gms; M.R: 185-190°C; 2-Butanol content: 13.35%.
Purity by HPLC: 99.92%; Diacid impurity: 0.06%; Amide alcohol impurity: Not detected; Isopropyl ester impurity: Not detected; Boc ester impurity: 0.02%; HR7I: 0.02%; Diastereomer impurity: Not detected. Chiral purity by HPLC: 99.97%; Enantiomer impurity: 0.03%.

A mixture of 5-(((S)-2-amino-3-(4-carbamoyl-2,6-dimethylphenyl)-N-((S)-l-(4-phenyl-lH-imidazol-2-yl)ethyl)propanamido)methyl)-2-methoxy benzoic acid 2-butanol solvate (100 gms), acetonitrile (150 ml) and water (150 ml) was stirred for 10 minutes at 25-30°C. Heated the reaction mixture to 40-45°C and stirred for 15 minutes at the same temperature. Filtered the reaction mixture through hyflow bed and washed with a mixture of acetonitrile and water. The filtrate was added to pre-cooled water at 0-5°C and stirred for 2 hours at the same temperature. Filtered the precipitated solid, washed with chilled water and dried to get the title compound.
Yield: 70.0 gms; M.R: 180-186°C; Water content: 5.17% w/w.
Purity by HPLC: 99.95%; Diacid impurity: 0.07%; Alcohol impurity: 0.01%; Isopropyl ester impurity: 0.02%; Boc ester impurity: 0.01%; HIUI: 0.07%. Chiral purity by HPLC: 99.98%; Enantiomer impurity: 0.02%.

we ^iaim:
1. Acid addition salts of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl) amino)methyl)benzoate compound of general formula-4.
Wherein, the acid is selected from hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, maleic acid, malonic acid, tartaric acid, mandelic acid, lactic acid, propionic acid, 2-chloromandelate, p-toluene sulfonic acid, ethane-l,2-disulfonic acid, camphor sulfonic acid, ethane sulfonic acid, methane sulfonic acid, naphthalene-2-sulfonic acid, benzene sulfonic acid, adipic acid, glutaric acid, glutamic acid, palmitic acid or aspartic acid, with the proviso that the acid is not formic acid, acetic acid, citric acid, oxalic acid, succinic acid, fumaric acid, malic acid.
2. Solid maleate salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl) amino)methyl)benzoate.
3. Crystalline maleate salt of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl) amino)methyl)benzoate.
4. Crystalline form-M of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl) amino)methyl)benzoate maleate salt compound of formula-4a characterized by its X-ray powder diffractogram having peaks at 8.1, 8.7, 9.6, 12.0, 15.2, 15.9, 17.6, 18.1, 18.6, 19.4, 19.6, 21.7, 22.5, 24.2, 24.9, 25.8, 26.4, 27.2, 28.7, 31.6 and 34.4 ± 0.2 degrees two-theta as illustrated in figure-1.
5. Crystalline form-S of (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl) amino)methyl)benzoate oxalate salt compound of formula-4b characterized by its X-ray powder diffractogram as illustrated in figure-2.

6. A process for the preparation of highly pure (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-
imidazol-2-yl)ethyl)amino)methyl)benzoate compound of formula-4, comprises of:
a. treating the compound of formula-4 with a suitable acid in a suitable solvent to provide
acid addition salts of compound of general formula-4,
b. treating the acid addition salts of compound of general formula-4 with a suitable base in
a suitable solvent to provide high pure (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-
imidazol-2-yl) ethyl)amino)methyl)benzoate compound of formula-4.
7. The process as claimed in claim-6, wherein in step-a) the suitable acid is selected from inorganic and organic acids; in step-a) & b) the suitable solvent is selected from chloro solvents, ketone solvents, ester solvents, alcohol solvents, ether solvents, hydrocarbon solvents, nitrile solvents, polar aprotic solvents and polar solvent like water and or there mixtures.
8. A process for the preparation of crystalline (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt compound of formula-4a, comprising of the following steps:
a. Adding suitable solvent to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)
ethyl)amino)methyl)benzoate compound of formula-4,
b. adding maleic acid to the reaction mixture,
c. stirring the reaction mixture,
d. filtering the precipitated solid to get the crystalline (S)-methyl-2-methoxy-5-(((l-(4-
phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate maleate salt compound of
formula-4a.
9. A process for the preparation of crystalline form-S of (S)-methyl-2-methoxy-5-(((l-(4-
phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt compound of formula-
4b comprising of the following steps:
a. Adding isopropanol to (S)-methyl-2-methoxy-5-(((l-(4-phenyl-lH-imidazol-2-yl)ethyl)
amino)methyl)benzoate compound of formula-4,
b. adding oxalic acid to the reaction mixture,
c. stirring the reaction mixture at 25-30°C,

d. filtering the precipitated solid to get the crystalline form-S of (S)-methyl-2-methoxy (((l-(4-phenyl-lH-imidazol-2-yl)ethyl)amino)methyl)benzoate oxalate salt compounc formula-4b.
10. Compounds having the following structural formulae: