Direct α-heteroarylation of amides (α to nitrogen) and ethers through a benzaldehyde-mediated photoredox reaction

Abstract

A photoredox reaction for cross-dehydrogenative coupling (CDC) was developed to C_α-arylate amides (α to nitrogen) and ethers using a variety of five- and six-membered electron-deficient heteroarenes. A unique decomposition mechanism of ammonium persulfate enhanced by photoexcited benzaldehydes was revealed. This benzaldehyde-mediated photoredox reaction proceeded smoothly with household 23 W CFL bulbs as the energy source under metal-free conditions, allowing the construction of new C_sp² -C_sp² and C_sp³ -C_sp² bonds and access to important pharmacophores of broad utility using commercially available reagents.