Metal-free cross-dehydrogenative C–N coupling of azoles with xanthenes and related activated arylmethylenes

AbstractA metal-free C(sp3)–H/N–H cross-coupling of azoles with xanthenes and related activated arylmethylenes is presented. Both the use of azoles and the activation pattern of C(sp3)–H sources are essential for this transformation. In the presence of 2.0 equiv of benzoyl peroxide (BPO), methylenes bearing a heteroatom-bridged bisaryl group reacted with various azolic N–H sources to afford C–N bond forming products in usually excellent or quantitative yields, and the diphenylmethane and methylenes coactivated by a phenyl group and an adjacent heteroatom are less reactive. Mechanistic investigations suggest that a radical/radical cross-coupling pathway might be involved.