Copper-Catalyzed 6-- Cyclization-Coupling of 2-Bromoaryl Ketones and Terminal Alkynes toward Naphthyl Aryl Ethers in Water.

The cyclization-coupling reaction of 2-bromoaryl ketones and terminal alkynes is first realized by copper catalysis, which produces polyfunctional naphthyl aryl ethers in moderate to excellent yields with broad substrate scope and good functional group tolerance. This reaction proceeds via 6-- cyclization and C(sp)-O coupling using green HO as the unique solvent and 5-bromopyrimidin-2-amine as the critical additive. Mechanistically, a unique Cu(III)-acetylide probably is the key intermediate, which allows exclusive 6-- selectivity.