Synthesis of alkyl thioamides by three-component reactions of allyl alcohols, elemental sulfur and amines: elemental sulfur as a mild oxidant and a sulfur source

An efficient and practical approach for the straightforward construction of thioamides via the combination of allyl alcohols, elemental sulfur and amines in a one-pot procedure was comprehensively achieved without any solvents or additives. Both substituted cinnamyl alcohols and linear allyl alcohols, as well as cyclic amines and long-chain primary amines, demonstrated good compatibility in the reaction, enabling the synthesis of a series of alkyl thioamides with yields up to 97%. Elemental S₈ served dual roles in the reaction as both the oxidant and the sulfur source, initially converting allyl alcohols into the corresponding allyl aldehydes and then into thioamides. The scale-up reaction worked well, demonstrating the potential application of the current reaction in organic synthesis.