Copper‐Catalyzed Highly Enantioselective Addition of a Silicon Nucleophile to 3‐Substituted 2H‐Azirines Using an Si−B Reagent

• Published in: Angewandte Chemie International Edition 2023-02, Vol.62 (7), p.e202215032-n/a
• Main Authors: Zhao, Zhi‐Yuan, Cui, Ming, Irran, Elisabeth, Oestreich, Martin
• Format: Article
• Language: English
• Subjects: Asymmetric Catalysis; Aziridines; Communication; Communications; Copper; Enantiomers; Imines; Nucleophiles; Nucleophilic Addition; Reagents; Silicon; Substitutes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202215032

3‐Substituted 2H‐azirines can be considered strained cyclic ketimines, and highly enantioselective addition reactions of silicon nucleophiles to either acyclic or cyclic ketimines have been elusive so far. The present work closes this gap for those azirines by means of a copper‐catalyzed silylation using a silyl boronic ester as a latent silicon nucleophile. The resulting C‐silylated, unprotected (N−H) aziridines are obtained in high yields and with excellent enantioselectivities and can be further converted into valuable compounds with hardly any erosion of the enantiomeric excess. The first catalytic asymmetric synthesis of C‐silylated, unprotected aziridines has been accomplished. Using a silyl boronic ester as a latent silicon nucleophile, a chiral copper catalyst enables its addition of 3‐substituted 2H‐azirines in high yields and with excellent enantioselectivities. These azirines can be considered strained cyclic and hence reactive ketimines, for which an effective silylation is still not known.