expansion of cyclic sulfonium ylides with acetylenic compounds was investigated. It was found that a six-membered cyclic sulfonium ylide (I) gave eight-membered ring expansion products (IIIa—e) in high yields under mild conditions on treatment with acetylenic compounds (IIa—e) in dimethyl sulfoxide. In a similar manner, the reactions of five- and seven-membered cyclic sulonium ylides with II afforded ring