Redox-neutral and metal-free synthesis of 3-(arylmethyl)chroman-4-ones via visible-light-driven alkene acylarylation

Abstract

A metal- and aldehyde-free visible-light-driven photoredox-neutral alkene acylarylation with readily available cyanoarenes is described. A variety of 3-(arylmethyl)chroman-4-ones (i.e., homoisoflavonoids) and analogs are efficiently synthesized with good functional group tolerance. This mild protocol relies on a phosphoranyl radical-mediated acyl radical-initiated cyclization and selective radical-radical coupling sequence, and is also further highlighted by subsequent derivatization to chromone and 2H-chromene as well as its application in the three-component alkene acylarylation.

Photoredox-Catalyzed Three-Component 1,2-Cyanoalkylpyridylation of Styrenes with Nonredox-Active Cyclic Oximes

“…Inspired by this, we envisioned whether such cyanoalkyl radicals derived from nonredox-active cyclic oximes could further undergo highly selective radical addition/radical–radical cross-coupling pathway to develop a class of more challenging three-component alkene 1,2-alkylpyridylation strategy, furnishing a class of architecturally elongated cyano-substituted alkylpyridines. In continuation of our research toward the phosphoranyl radical-mediated deoxygenation, , we herein report an example of photoredox-catalyzed three-component 1,2-cyanoalkylpyridylation of styrenes with nonredox-active cyclic oximes; a wide variety of styrenes, cyanopyridines, and cyclic oximes could be smoothly transformed into a series of structurally diverse β-cyanoalkylated alkylpyridines with good yields and functional group compatibility (Scheme C). More importantly, it is easily accessible for the late-stage modification of complex bioactive molecules, thus providing a facile route for application in drug discovery and development.…”