A novel and general strategy has been developed for the synthesis of γ-keto sulfones via Bro̷nsted-acid-promoted tandem sulfonylation of propargylic esters with RSO2H under metal-free and oxidant-free conditions. The novel transformation proceeds through α,β-unsaturated ketone intermediates as the key intermediate, which then undergoes thia-Michael addition with sulfinic acids to afford the target γ-keto sulfones in moderate to excellent yields. The key merits of this approach include operational simplicity, the avoidance of metals and oxidants, and good functional group tolerance.
Wang et al. (Wed,) studied this question.