Copper-Mediated Dichotomic Borylation of Alkyne Carbonates: Stereoselective Access to (E)-1,2-Diborylated 1,3-Dienes versus Traceless Monoborylation Affording α-Hydroxyallenes

Kun Guo; Arjan W Kleij

doi:10.1002/anie.202014310

Copper-Mediated Dichotomic Borylation of Alkyne Carbonates: Stereoselective Access to (E)-1,2-Diborylated 1,3-Dienes versus Traceless Monoborylation Affording α-Hydroxyallenes

Angew Chem Int Ed Engl. 2021 Feb 23;60(9):4901-4906. doi: 10.1002/anie.202014310. Epub 2021 Jan 14.

Authors

Kun Guo¹, Arjan W Kleij^{1

2}

Affiliations

¹ Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
² Catalan Institute of Research and Advanced Studies (ICREA), Pg. Lluís Companys 23, 08010, Barcelona, Spain.

PMID: 33230901
DOI: 10.1002/anie.202014310

Abstract

A mild copper-mediated protocol has been developed for borylation of alkynyl cyclic carbonates. Depending on the nature of the borylating reaction partner, either stereoselective diborylation of the propargylic surrogate takes place, providing convenient access to (E)-1,2-borylated 1,3-dienes, or traceless monoborylation occurs, which leads to α-hydroxyallenes as the principal product. The dichotomy in this borylation protocol has been scrutinized by several control experiments, illustrating that a relatively small change in the diboron(4) reagent allows for competitive alcohol-assisted protodemetalation to forge an α-hydroxyallene product under ambient conditions.

Keywords: alkyne carbonates; borylation; copper; dichotomy; homogeneous catalysis.

Publication types

Research Support, Non-U.S. Gov't