Photoredox-Controlled β-Regioselective Radical Hydroboration of Activated Alkenes with NHC-Boranes.

In this Communication, we report an unprecedented β-regioselective radical inverse hydroboration (compared with ionic hydroboration) of α,β-unsaturated amides with NHC-BH3 enabled by photoredox catalysis. Density functional theory (DFT) calculations show that the unique photoredox cycle is a key factor to control the β-regioselective radical hydroboration, by lowering the energy barrier in comparison with other pathways. This protocol provides a general and convenient route to construct a wide range of structurally diverse β-borylated amides in synthetically useful yields under mild conditions.