Synthesis and Addition Reactions of 1,3‐Thiazole‐5(4 H )‐thione Oxides

1,3‐Thiazole‐5(4 H )‐thione oxides 2 were prepared by oxidation of the corresponding 1,3‐thiazole‐5(4 H )‐thiones 1 with m ‐chloroperbenzoic acid ( Table 1 ). Addition reactions of 2 with organolithium and Grignard reagents yielded 4,5‐dihydro‐4,4‐dimethyl‐1,3‐thiazol‐5‐yl methyl sulfoxides of type 4 via thiophilic attack ( Table 2 ). Whereas the reaction with the organolithium compounds proceeded with fair‐to‐excellent yields, the Grignard reagents reacted only very sluggishly. The sulfoxides 4 could also be prepared via oxidation of 4,5‐dihydro‐4,4‐dimethyl‐5‐(methylthio)‐1,3‐thiazoles of type 3 with m ‐chloroperbenzoic acid, together with the corresponding sulfones 5 ( Scheme 1 ).