Tetrahydroxydiboron-Promoted Radical Addition of Alkynols

Org Lett. 2020 Aug 7;22(15):6214-6219. doi: 10.1021/acs.orglett.0c02367. Epub 2020 Jul 19.

Abstract

Tetrahydroxydiboron has previously been used as a borylation or reducing reagent in organic synthesis. Herein, we present a novel tetrahydroxydiboron-promoted radical addition of internal alkynes followed by intramolecular oxidation of alcohol through 1,5-hydrogen atom transfer. Preliminary mechanistic studies showed that the process might be initiated through N,N-dimethylformamide-assisted homolytic cleavage of tetrahydroxydiboron. This process provides a convenient synthesis of fluoroalkyl-substituted alkenes with a pendant aldehyde or ketone moiety.