Radical Addition to Strained σ-Bonds Enables the Stereocontrolled Synthesis of Cyclobutyl Boronic Esters

Silvi, Mattia; Aggarwal, Varinder K.

Abstract

While radical additions to π-bonds are well established, additions to σ-bonds are far less explored. We have found that electron deficient radicals derived from alkyl iodides under visible light irradiation add to the central strained bond of bicyclobutyl (BCB)-boronate complexes and lead to 1,3-alkyl disubstituted cyclobutyl boronic esters in high yields, with full stereospecificity and high levels of stereoselectivity. Novel cyclobutyl-substituted structures, including peptide and steroid boronic ester derivatives can be accessed. Additionally, although the use of electron-rich alkyl iodides as radical precursors was found to be ineffective, an alternative route involving alkylsulfonylation of the BCB-boronate followed by reductive desulfonylation provided access to simple alkyl substituted cyclobutane products.

Citation

Silvi, M., & Aggarwal, V. K. (2019). Radical Addition to Strained σ-Bonds Enables the Stereocontrolled Synthesis of Cyclobutyl Boronic Esters. Journal of the American Chemical Society, 141(24), 9511-9515. https://doi.org/10.1021/jacs.9b03653

• Journal Article Type: Article
• Acceptance Date: May 29, 2019
• Online Publication Date: May 29, 2019
• Publication Date: Jun 19, 2019
• Deposit Date: Jan 29, 2020
• Publicly Available Date: May 30, 2020
• Journal: Journal of the American Chemical Society
• Print ISSN: 0002-7863
• Electronic ISSN: 1520-5126
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 141
• Issue: 24
• Pages: 9511-9515
• DOI: https://doi.org/10.1021/jacs.9b03653
• Public URL: https://nottingham-repository.worktribe.com/output/3826241
• Publisher URL: https://pubs.acs.org/doi/10.1021/jacs.9b03653
• Additional Information: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/jacs.9b03653