Affiliation:
1. Department of Applied Chemistry Faculty of Science and Technology Keio University 3-14-1, Hiyoshi, Kohoku-ku Yokohama 223-8522 Japan
Abstract
AbstractA reductive (3+2) annulation of lactams through iridium‐catalyzed hydrosilylation and photoredox coupling with α‐bromoacetic acid was developed. The iridium‐catalyzed hydrosilylation of the lactam carbonyl group and subsequent elimination provide a transient cyclic enamine, which undergoes iridium‐catalyzed photoredox coupling with α‐bromoacetic acid in a one‐pot process. The developed conditions show high functional‐group tolerance and provide cyclic N,O‐acetals containing a quaternary carbon center. The resulting N,O‐acetals undergo a variety of acid‐mediated nucleophilic addition reactions via iminium ions to give substituted cyclic amines. The developed sequence including reductive (3+2) annulation and acid‐mediated nucleophilic addition was successfully applied to the four‐step total synthesis of (±)‐eburnamonine.