PROCESS FOR PREPARATION OF 7-DEHYDROCHOLESTEROL

摘要

The invention discloses an improved cost-effective process for preparation of 7-Dehydrocholesterol of formula I with good yield and purity, comprising:a) epimerizing 7(alpha+beta) bromo protected cholesterol in presence of tetrabutyl ammonium bromide in toluene or a ketonic solvent or combinations thereof to obtain predominantly 7.alpha-bromo 3-protected cholesterol; b) Reacting 7.apha-bromo 3- protected cholesterol with substituted or unsubstituted thiophenol or its salts in presence of a liquor ammonia to obtain predominantly 7.beta.-thiophenyl)-3-protected cholesterol; c) Oxidizing 7. beta. - thiophenyl 3-protected cholesterol in presence of Cumene hydrogen peroxide and Titanium tetraisopropoxide to obtain 7. beta. -phenyl sulfoxide 3-protected cholesterol; d) Converting 7. beta. -phenyl sulfoxide 3-protected cholesterol into 7-Dehydro 3-protected cholesterol in presence of base; e) purifying 7-Dehydro 3-protected cholesterol by suspending in a suitable organic solvent; and f) Deprotecting the 7-Dehydro 3-protected cholesterol by treating with alkali in presence of methanol to obtain 7-Dehydrocholesterol followed by purification of 7-Dehydrocholesterol from an organic solvent.