Syngas-Free Highly Regioselective Rhodium-Catalyzed Transfer Hydroformylation of Alkynes to α,β-Unsaturated Aldehydes.

The hydroformylation of alkynes is a fundamental and important reaction in both academic research and industry. Conventional methods focus on the conversion of alkynes, CO, and H2 into α,β-unsaturated aldehydes, but they often suffer from problems associated with operation, regioselectivity, and chemoselectivity. Herein, we disclose an operationally simple, mild, and syngas-free rhodium-catalyzed reaction for the hydroformylation of alkynes via formyl and hydride transfer from an alkyl aldehyde. This synthetic method uses inexpensive and easy-to-handle n-butyraldehyde to overcome the challenge posed by the use of syngas in traditional approaches and employs a commercially available catalyst and ligand to transform a broad range of internal alkynes, especially alkynyl-containing complex molecules, into versatile stereodefined α,β-unsaturated aldehydes with excellent chemo-, regio-, and stereoselectivity.