Photoredox/Nickel Dual-Catalyzed Allylation of Aldehydes with Allylic Alcohols and Mechanistic Insights in the Presence of CO2

Direct utilization of allylic alcohols as allylic reagents without metal reductants has drawn significant attention. Herein, we report a practical, diastereoselective photoredox/Ni(II)-dual-catalyzed reductive allylation reaction of aldehydes with readily accessible allylic alcohols in the presence of CO2. This methodology allows the branched regioselective direct allylation of a wide range of aldehydes with various allylic alcohols in good to high yield and up to >20:1 d.r. ratio. Accurate DFT calculations revealed the rationale behind the diastereoselectivity differences via Zimmerman–Traxler transition state for different substrates, while also delineated the energetically most favorable mechanistic pathway for this allylation reaction.