Patent ID: 9409855
Filing Date: 2016-08-09
CPC Classification: C07C

Claim Text:
1. A process for asymmetric synthesis of enantiomerically pure venlafaxine with ee≧99% comprising the steps of: a. reacting anisaldehyde with nitromethane in mole ratio 1:11.8 in presence of ammonium acetate in acetic acid under sonication condition at room temperature ranging between 25-35° C. for a period ranging between 2-4 hrs to obtain nitro styrene; b. michael addition of nitrostyrene as obtained in step (a) with cyclohexanone in mole ratio 1:5 in presence of proline based organocatalyst under stirring at room temperature ranging between 25-35° C. for a period ranging between 23-25 hrs in the presence of p-toluene sulphonic acid to obtain nitro ketone; c. reducing nitro ketone of step (b) using NaBH d. treating amino alcohol of step (c) with mesyl chloride in presence of Et e. subjecting compound (R)-2-(cyclohex-1-en-1-yl)-2-(4-methoxyphenyl)ethyl)carbamate of step (d) with NaH and MeI in dry THF to obtain benzyl (R)-(2-(cyclohex-1-en-1-yl)-2-(4-methoxyphenyl)ethyl)(methyl)carbamate; f. epoxidation of benzyl (R)-(2-(cyclohex-1-en-1-yl)-2-(4-methoxyphenyl)ethyl)(methyl)carbamate of step (e) by treating with m-CPBA in presence of NaHCO g. subjecting the crude epoxide of step (f) to selective epoxide opening as well as carbamate reduction in one pot using lithium aluminum hydride at reflux condition at temperature ranging between 65-70° C. for a period ranging 4-5 hrs in THF to afford (−)-venlafaxine.