Syntheses with sulfones XLVIII : stereoselective synthesis of 2-isopropyl 1,4-dienes through the iron-catalysed cross-coupling reaction of 2-benzenesulfonyl 1,4-dienes and isopropylmagnesium chloride

Abstract

The stereoselective synthesis of 2-isopropyl 1,4-dienes through the cross-coupling reaction of 2-benseneaulfonyl 1,4-diene e and isopropylmagnesium chloride under transition-metal catalysis is described. Iron salts, which were better catalysis than palladium or nickel ones, led to substitution, of the sulfonyl group with > 97% stereospecifcity and without isomerisation of the isopropyl Grignard moiety to the n-propyl derivative. Notable amounts of the compound resulting from reduction of the sulfonyl group were also formed.