Rhodium-Catalyzed Anti-Markovnikov Intermolecular Hydroalkoxylation of Terminal Acetylenes

We report here the first transition-metal-catalyzed anti-Markovnikov intermolecular hydroalkoxylation of terminal acetylenes to give enol ethers in high yields without using bases. Arylacetylenes as well as alkenyl- and alkylacetylenes were coupled with aliphatic alcohols, and the products were obtained with high Z selectivity in most cases. Effective catalysts were 8-quinolinolato rhodium complexes, which are structurally simple but have been relatively unexplored as catalysts.