Regiodivergent Metal-Catalyzed Oxidative Alkynylation of 2-Arylthiazoles with Terminal Alkynes under Air Conditions.

Regiodivergent transition-metal-catalyzed oxidative C5- and ortho-alkynylation of 2-arylthiazoles have been demonstrated. Namely, Pd(II)-catalysis selectively generated C5-alkynylated products from the reaction of 2-arylthiazoles and terminal alkynes. In contrast, Ru(II)-catalysis exclusively provided ortho-alkynylated products from the same substrates. This protocol features a wide substrate scope, good functional group tolerance, high atom-economy, and exclusive regioselectivity. The alkynylated products can be readily converted into highly valuable synthons, which hold potential for applications in the fields of medicinal chemistry and materials science.