Patent ID: 8440844

Claim:
A process for the preparation of chirally pure β-amino alcohol of general formula 1A wherein R 1 and R 2 =ethyl, methyl, isopropyl or trifluoromethyl, comprising the steps of: a) adding a ketone, triethyl phosphonoacetate, NaH and THF at temperature ranging between −10° C. to 10° C. for a period ranging between 5-15 h to obtain α,β-unsaturated ester; b) hydrogenating α, the β-unsaturated ester as obtained in step (a) with H 2 gas and in the presence of a catalyst for a period ranging between 12 h to 24 h at temperature ranging between 15° C. to 35° C. to obtain saturated primary alcohol; c) oxidising the alcohol as obtained in step (b) with IBX (o-iodoxy benzoic acid) in DMSO for a period ranging between 1 h to 4 h at temperature ranging between 10° C. to 35° C. to obtain aldehyde; d) α-aminating the aldehyde as obtained in step (c) using List's protocol for a period ranging between 2 h to 8 h at temperature ranging between −10° C. to 10° C. to obtain protected amino alcohol; e) hydrogenating the protected amino alcohol as obtained in step (d) with Raney nickel over hydrogen in presence of methanol and acetic acid for a period ranging between 22 h to 48 h at temperature ranging between 15° C. to 35° C. to yield intermediate alcohol; and f) condensing the intermediate alcohol as obtained in step (e) with 5-chlorothiophene-2-sulfonyl chloride in the presence of triethylamine for a period ranging between 30 min to 6 h at temperature ranging between −10° C. to 15° C. to yield β-amino alcohol of general formula 1A.