Palladium‐Catalyzed Direct Cross‐Dehydrogenative Alkynylation of Selenophenes

Abstract

A palladium‐catalyzed (Pd(PPh3)4/Ag2O/PivOH) C2‐regioselective direct dehydrogenative alkynylation of unsubstituted selenophene was achieved. The selenophenes substituted with R1 groups at 2‐position can be C5‐alkynylated with a variety of 4‐substituted phenylacetylenes (R2 groups). The R1 and R2 can be either electron‐withdrawing or electron‐donating groups, demonstrating a wide range of substrate scope with various functional group tolerance. The mono/C2‐alkynylated selenophenes can subsequently undergo the second direct alkynylation at C5‐position to afford symmetrical or unsymmetrical donor‐π‐acceptor 2,5‐dialkynylated selenophenes.