Crystalline Form of y-Aminobutyric Acid Analog

Abstract

A crystalline form of a γ-aminobutyric acid analog, and methods of preparing same, are provided.

1 .- 9 . (canceled) 
     
     
         10 . A method for preparing crystalline 1-{[(α-isobutanoyloxyethoxy)carbonyl]aminomethyl}-1-cyclohexane acetic acid comprising:
 heating 1-{[(α-isobutanoyloxyethoxy)carbonyl]aminomethyl}-1-cyclohexane acetic in a solvent or a solvent mixture to provide a solution; and 
 cooling the solution to provide crystalline 1-{[(α-isobutanoyloxyethoxy)carbonyl]aminomethyl}-1-cyclohexane acetic acid. 
 
     
     
         11 . The method of  claim 10 , wherein the solvent is selected from the group consisting of methanol, ethanol, 1,2-propane diol, t-butanol, n-butanol, isopropanol, acetic acid, nitromethane, acetonitrile, dimethylsulfoxide, dimethylformamide, N-methyl pyrrolidone, acetone, methyl acetate, ethyl acetate, isopropyl acetate, isobutyl acetate, methyl isobutyl ketone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, toluene, methyl t-butyl ether, chlorobenzene, 1,4-dioxane, diethyl ether, cumene, o-xylene, m-xylene, p-xylene, 2-ethoxyethanol, 1,2-ethandiol, ethyl formate, 2-methoxyethanol, 1-pentanol, anisole, dichloromethane, cis and trans 1,2-dichloroethylene, chloroform, dimethylacetamide, propylacetate and mixtures thereof. 
     
     
         12 . The method of  claim 10 , wherein the solvent is a solvent combination comprising a solvent and an anti-solvent. 
     
     
         13 . The method of  claim 12 , wherein the anti-solvent is selected from the group consisting of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, cis or trans decalin, cyclohexane, methylcyclohexane and mixtures thereof. 
     
     
         14 . The method of  claim 13 , wherein the solvent combination comprises ethyl acetate and heptane and the temperature of heating is between about 50° C. and reflux. 
     
     
         15 . The method of  claim 14 , wherein the temperature is about 70° C. 
     
     
         16 . The method of  claim 15 , wherein the concentration of 1-{[(α-isobutanoyloxyethoxy)carbonyl]aminomethyl}-1-cyclohexane acetic acid in the ethyl acetate/heptane mixture is between about 0.18 g/mL and about 0.22 g/mL. 
     
     
         17 . The method of  claim 12 , wherein the solvent is a solvent combination comprising methyl t-butyl ether and methylcyclohexane and the temperature of heating is in the range of between about 20° C. to about 40° C. 
     
     
         18 . The method of  claim 17 , wherein the concentration of 1-{[(α-isobutanoyloxyethoxy)carbonyl]aminomethyl}-1-cyclohexane acetic acid in the solvent combination is between about 0.1 g/mL and about 0.25 g/mL. 
     
     
         19 . The method of  claim 18 , wherein the solution is cooled to a temperature between about 0° C. and about 25° C.