Photoinduced Reductive Coupling of Aliphatic Aldehydes with Vinyl/Alkynyl Halides to Access Allylic and Propargylic Alcohols via a Ligated Boryl Radical.

The synthesis of allylic and propargylic alcohols has traditionally relied on preformed organometallic reagents, stoichiometric metal reductants, or transition metal catalysts. Herein, we report a photoinduced, metal-free strategy that generates a ligated boryl radical in situ to activate aliphatic aldehydes, enabling their direct coupling with vinyl halides and alkynyl bromides to afford the corresponding allylic and propargylic alcohols. This method exhibits broad functional group tolerance and is applicable to the late-stage modification of complex molecules. Gram-scale synthesis and product derivatizations further demonstrate the synthetic utility of this protocol.