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.