Reactions of carbonyl-stabilized sulphonium ylides with grignard reagents

Sulphonium diacylmethylides RR′-;(COR′)2react with R′'‴MgX to afford ketones R′COR′'′, if either R′' or R′'′ has an α-hydrogen. In the absence of this, for example, the reaction of R(Me)(COPh)2with PhMgBr results in elimination of the S-;Me and gives a product RSC(COPh2. If R, R′, R′' and R‴ are all Ph groups, benzophenone and Ph2HCOPh are formed. The reaction of phenacylides R(Me)HCOPh with R‴MgX proceeds with elimination of R‴Me to produce RSCH2COPh. Reactions of PhLi with these ylides are also recorded.