Enantiomerically pure 1,3,2-dioxaborolanes: new reagents for the hydroboration of alkynes
Abstract
Stable, enantiomerically pure alkenylboronic esters 2 are conveniently prepared by direct hydroboration employing the new 1,3,2-dioxaborolane 4; their highly diastereoselective cyclopropanation can be achieved.