Synthesis and Reactions of 4-Dimethylsulfuranylidene-2,3-dioxotetrahydrofuran Derivatives

The cyclic sulfonium ylides, 4-dimethylsulfuranylidene-2,3-dioxotetrahydrofuran derivatives (8), were synthesized in good yields by reactions of methyl and ethyl dimethylsulfuranylidenepyruvates (3 and 4) with carbonyl compounds. The reactions of 8 with p-toluenesulfonyl chloride and benzoyl chloride gave 4-methylthio-3-(p-toluenesulfonyloxy)- and 4-methylthio-3-benzoyloxy-2-oxo-2,5-dihydrofuran derivatives respectively in high yields. The ylides (8) reacted with mercaptans to afford 4-substituted products (14–16), whereas, on the reactions with thiourea, the demethylation of the dimethylsulfonium group proceeded exclusively.