Stereoselective sulfenylation of oxindole-derived propargyl alcohols to access sulfenylated-3-alkenyloxindoles.

A Ca-catalyzed, tetrasubstituted alkenyl-sulfenylation was achieved using readily available aryl/alkyl thiols and easily prepared oxindole-derived propargyl alcohols under solvent-free conditions. The reaction proceeded with hydrogen bonding assisted regioselective α-thiolation and subsequent calcium catalyzed stereoselective alkenylation to yield E-alkenyl thioethers with high diastereoselectivity.