Patent ID: 8288565

Claim:
A process for preparing (2S,3aR,7aS)-Octahydro-1H-indole-2-carboxylic acid hydrochloride (5) comprising the steps of: (a) N-alkylation of (1S,2S)-2-[(S)-1-phenylethyl amino]cyclohexyl)methanol (11) with ethyl chloroacetate or ethyl bromoacetate in the presence of a base to give ethyl 2-(((1S,2S)-2-(hydroxymethyl)cyclohexyl)((S)-1-phenylethyl)amino)acetate (13), (b) conversion of ethyl 2-(((1S,2S)-2-(hydroxymethyl)cyclohexyl)((S)-1-phenylethyl)amino)acetate (13) to a compound of formula (14) wherein R 3 is a leaving group selected from the group consisting of mesylate, triflate, tosylate, methanesulfonate ester, trifluoromethane sulfonate ester, chloride, bromide, and iodide, (c) treatment of the compound of formula (14) with a base to provide (2S,3aR,7aS)-ethyl 1-((S)-1-phenylethyl)octahydro-1H-indole-2-carboxylate (15), (d) cleavage of the N-Î±-methylbenzyl group of (2S,3aR,7aS)-ethyl 1-((S)-1-phenylethyl)octahydro-1H-indole-2-carboxylate (15) by hydrogenolysis to afford (2S,3aR,7aS)-ethyl octahydro-1H-indole-2-carboxylate (16), optionally followed by acidification to provide the hydrochloride salt of the compound of formula (16), and (e) acid hydrolysis of (2S,3aR,7aS)-ethyl octahydro-1H-indole-2-carboxylate (16) or the hydrochloride salt thereof to provide (2S,3aR,7aS)-octahydro-1H-indole-2-carboxylic acid hydrochloride (5),