Phosphine‐Catalyzed Divergent γ,γ‐ and ε,γ‐Umpolung Domino Additions of Bisoxindoles with Allenoates: Construction of Vicinal All‐Carbon Quaternary Stereocenters and Formal Total Synthesis of Dimeric Cyclotryptamine Alkaloids
Yufei Zhang, Jing Chen, Hui Yao, Yuanbin Wang, Hongyu Liu, Long Wang, Nianyu Huang, Nengzhong Wang
Abstract
Comprehensive Summary Vicinal all‐carbon quaternary stereocenters are widely present in natural products and bioactive molecules. However, the construction of such motif in one step from readily available starting materials remains a significant challenge. Herein, we report a phosphine‐catalyzed divergent γ,γ‐ and ε,γ‐umpolung domino addition of bisoxindoles with allenoates. This method serves as a practical tool for the concise synthesis of a series of bisoxindole derivatives bearing sterically hindered vicinal all‐carbon quaternary stereocenters under mild reaction conditions. The applicability of this novel method was demonstrated with the gram‐scale synthesis of three known advanced intermediates for the total syntheses of calycanthine, chimonanthine and folicanthine.