Transition metal-free radical trans-hydroboration of alkynes with NHC-boranes via visible-light photoredox catalysis

Abstract

The development of radical hydroboration of alkynes remains an important challenge. Here we report transition metal-free trans-hydroboration of alkynes with NHC-boranes via the synergistic merger of 4CzIPN as the photoredox organocatalyst and 4-CF₃-PhSH as the hydrogen atom transfer (HAT) catalyst. This protocol provides a practical, efficient and sustainable strategy to construct a wide range of diverse (E)-alkenylboranes with high regio- and stereoselectivity under mild conditions. Notably, the unique photoredox catalytic system is a key factor in controlling the reaction efficiency and selectivity.