Patent ID: 8304578

Claim:
A process for preparing 1-[2-(dimethylamino)-1-(4-phenol)ethyl]cyclohexanol (O-desmethylvenlafaxine) or its pharmaceutically acceptable salt thereof, wherein the process comprises: (a) reducing 1-[cyano(substituted benzyloxyphenyl) methyl] cyclohexanol of formula (II) with reducing agent sodiumborohydride-iodine or sodiumborohydride-trifluoroacetic acid in presence of a solvent to obtain 1-[2-amino-1-(substituted benzyloxyphenyl)ethyl]cyclohexanol of formula (III); wherein R is selected from phenyl, nitrophenyl, hydroxyphenyl or halophenyl; (b) alkylating the 1-[2-amino-1-(substituted benzyloxyphenyl)ethyl]cyclohexanol of formula (III) to obtain compound of formula IV; and (c) deprotecting the compound of formula (IV) to obtain O-desmethylvenlafaxine.