Regio- and stereoselective oxidative conversion of alkynes to sulfenylated α,β-unsaturated carbonyls

The synthesis of enone moieties via the oxidation of internal alkynes under varied conditions is known. The use of propargyl units as the precursors of alpha,beta-unsaturated aldehydes is rare. Herein, we present the synthesis of alpha-sulfenylated alpha,beta-unsaturated aldehydes from terminal alkynes through the selective addition of a suitable oxidant to the key thiirenium ion intermediates. The mild conditions of this protocol enable the conversion of a vast range of terminal alkynes, bearing various functionalities or derived from drug and bioactive molecules, to their alpha,beta-unsaturated aldehyde analogues with excellent chemo-, regio- and stereoselectivities.