Visible-Light-Driven Borylacylation of Alkenes by NHC/Photoredox Dual Catalysis: Accessing Boryl 1,4-Dicarbonyl Architectures

Abstract

Boron-containing carbonyl compounds serve as versatile synthons in organic synthesis, materials science, and medicinal chemistry, with boryl dicarbonyl compounds emerging as privileged precursors for the construction of borylated heterocycles. Despite their utility, efficient synthesis of these architectures from readily available starting materials remains challenging, particularly those requiring concurrent borylation and acylation. Herein, we present a transition-metal-free strategy for modular assembly of boryl 1,4-dicarbonyl compounds via synergistic photoredox/N-heterocyclic carbene (NHC) dual catalysis. The reaction proceeds through regioselective alkene difunctionalization involving NHC-attached ketyl and NHC-boryl radicals, achieving good chemo- and diastereoselectivity. This protocol demonstrates broad functional group tolerance (44 examples) and scalability (gram-scale synthesis), while mechanistic studies (radical blocking and electron paramagnetic resonance (EPR) detection) corroborate the generation and coupling of two radical species. The synthetic versatility is further highlighted by downstream transformations into pharmaceutically relevant multisubstituted boryl γ-lactones and 1,2-benzazaborines.