<i>trans</i>‐Hydroboration of Propargyl Alcohol Derivatives and Related Substrates

Abstract

The hydroboration of internal alkynes with pinacolborane as the reagent catalyzed by [Cp*RuCl]₄ results in good to excellent levels of regio- as well as stereoselectivity, provided that the triple bond bears one linear and one singly-branched substituent. In such cases, the reaction follows an unusual trans-addition mode and places the boron entity distal to the branching point. The resulting alkenyl boronates, which are difficult to make otherwise, can be engaged in numerous enabling downstream processes.