Visible-light-driven NHC and organophotoredox dual catalysis for the synthesis of carbonyl compounds

Over the past two decades, organocatalyzed visible-light-mediated radical chemistry has significantly influenced modern synthetic organic chemistry. In particular, dual catalysis combining <i>N</i>-heterocyclic carbenes (NHCs) with organophotocatalysts (e.g., 4CzIPN, eosin Y, rhodamine, 3DPAFIPN, Mes-Acr-Me⁺ClO₄ ^-) has emerged as a powerful photocatalytic strategy for efficiently constructing a wide variety of carbonyl compounds via radical cross-coupling processes. This cooperative organic dual catalysis has great potential in medicinal, pharmaceutical, and materials science applications, including the development of organic semiconductors and polymers. In recent years, NHC-involved photocatalysis has attracted considerable attention in synthetic organic chemistry, and particularly in the late-stage functionalization of bioactive compounds, drugs, and natural products. This review highlights recent advances in NHC-organophotoredox dual catalysis, focusing on methodology development, mechanistic insights, and reaction scope for synthesizing carbonyl compounds and pharmaceutically relevant intermediates. Moreover, this catalytic system operates under green and sustainable conditions, tolerating a broad range of functional groups and substrate scope, and utilizes low-cost, atom-economical, non-toxic starting materials.