An asymmetric alkynylation/hydrothiolation cascade: an enantioselective synthesis of thiazolidine-2-imines from imines, acetylenes and isothiocyanates

A multicomponent reaction between imines, terminal alkynes, and isothiocyanates in the presence of a catalytic chiral copper-pybox complex proceeds enantioselectively to give enantiopure thiazolidine-2-imines (60-99% ee) via a highly regioselective intramolecular 5-exo-dig hydrothiolation reaction.