Facile Access to Cyclopropylboronates via Stereospecific Deborylative Cyclization: A Leaving Group‐Assisted Activation of Geminal Diborons

• Published in: Angewandte Chemie International Edition Vol. 62; no. 21; pp. e202302638 - n/a
• Main Authors: Chen, Xin‐Yi, Gao, Feng‐Chen, Ning, Peng‐Fei, Wei, Yi, Hong, Kai
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 15.05.2023
• Edition: International ed. in English
• Subjects: Cyclopropanes; Deborylative Cyclization; Epoxides; Functional groups; Optical activity; Organoboron; Stereoselectivity; Stereospecific Reaction; Stereospecificity; Synthetic Methods; Transition metals; Cyclopropanes; Deborylative Cyclization; Synthetic Methods; Organoboron; Stereospecific Reaction
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202302638

Herein we reported a transition metal‐free deborylative cyclization strategy, based on which two routes have been developed, generating racemic and enantioenriched cyclopropylboronates. The cyclization of geminal‐bis(boronates) bearing a leaving group was highly diastereoselective, tolerating a few functional groups and applicable to heterocycles. When optically active epoxides were used as the starting materials, enantioenriched cyclopropylboronates could be efficiently prepared with >99 % stereospecificity. Mechanistic studies showed that the leaving group at the γ‐position played a crucial role and significantly promoted the activation of the gem‐diboron moiety. A transition metal‐free deborylative cyclization strategy led to the efficient synthesis of racemic and enantioenriched cyclopropylboronates. The cyclization of geminal‐bis(boronates) bearing a leaving group was highly diastereoselective and stereospecific, tolerating various functional groups and heterocycles. Mechanistic studies indicated that the leaving group at the γ‐position significantly promoted the activation of the gem‐diboron moiety.