Dual Photoredox and Titanium Catalyzed Regioselective Allenylation of Aldehydes via Reductive Radical‐Polar Crossover

作者：Zulin Xiao, Wenzhe Shang, Tao Huang, Lei He, Jingyao Li, Shen Luo, Xiaoxia He, Xiang Li, Fusheng Li · 发表于：Chinese Journal of Chemistry · 年份：2024 · DOI：10.1002/cjoc.202400705 · 被引用次数：8 · 研究领域：Radical Photochemical Reactions、Catalytic C–H Functionalization Methods、Sulfur-Based Synthesis Techniques

Comprehensive Summary The direct reductive coupling of carbonyl compounds with propargyl halides is a powerful and reliable tool in the synthesis of α‐allenols. However, stoichiometric metal reductants, harsh reaction conditions and a variety of additional additives are required in the traditional strategies. Additionally, the reactivity and regioselectivity control remains an elusive challenge. Herein, we developed the Ti‐catalyzed regioselective reductive coupling of readily available aldehydes and racemic propargyl bromides to rapidly access a wide range of α‐allenols. This method proceed efficiently in a reductive radical‐polar crossover manner featuring mild conditions, excellent regioselectivity control, broad substrate scope, and eco‐friendliness. Preliminary mechanistic studies support the radical‐involved catalytic cycle. And the DFT calculations demonstrate that the regioselectivity is determined by the Zimmerman‐Traxler‐type transition states.