Patent ID: 6395901
Filing Date: 2002-05-28
Classification: A61P,C07D

Abstract:
A process for the preparation of a compound of formula VI, wherein R4 is a saturated or unsaturated C1-8 alkyl radical, comprising the following steps:a) reacting a compound of formula I wherein R1 represents a saturated or unsaturated C1-8 alkyl residue, with 3-halo-propionyl chloride or 2-halo-propionyl chloride in an aprotic organic solvent in the presence of a proton acceptor;b) reacting the compound or mixture of compounds obtained in step a) with calcium borohydride in tetrahydrofuran at a temperature of between 10 and 65Â° C.; c) reacting the compound obtained in step b) in an aprotic organic solvent with an alkylsulphonyl chloride in the presence of a proton acceptor; d) reacting the compound obtained in step c) in an aprotic organic solvent with a compound of formula R4SX, wherein R4 has the meaning given above and X is an alkali metal; and e) converting the compound obtained in step d) to compound VI by treatment with a reducing agent in an aprotic organic solvent.