Oxyallyl Cation Capture via Electrophilic Deborylation of Organoboronates: Access to α, α'-Substituted Cyclic Ketones

Truong N Nguyen; Krit Setthakarn; Jeremy A May

doi:10.1021/acs.orglett.9b02831

Oxyallyl Cation Capture via Electrophilic Deborylation of Organoboronates: Access to α, α'-Substituted Cyclic Ketones

Org Lett. 2019 Oct 4;21(19):7837-7840. doi: 10.1021/acs.orglett.9b02831. Epub 2019 Sep 19.

Authors

Truong N Nguyen¹, Krit Setthakarn¹, Jeremy A May¹

Affiliation

¹ Department of Chemistry , University of Houston , 3585 Cullen Boulevard, Fleming Building Room 112 , Houston , Texas 77204-5003 , United States.

PMID: 31536365
DOI: 10.1021/acs.orglett.9b02831

Abstract

An umpolung strategy to synthesize α,α'-substituted cyclic ketones through the nucleophilic addition of organoboronates to α-hydroxyl silyl enol ethers is described. The reaction proceeds via the trapping of in situ generated oxyallyl cations via the electrophilic deborylation of C(sp²) and C(sp) borates. This efficient and straightforward method provides direct access to α-substituted silyl enol ethers in high yield with complete regioselectivity. Desilylation in a one-pot procedure provides the corresponding α,α'-disubstituted ketones with high diastereoselectivity.