Palladium(II)-Catalyzed Direct ortho-C-H Acylation of Anilides by Oxidative Cross-Coupling with Aldehydes using tert-Butyl Hydroperoxide as Oxidant

摘要

An efficient palladium-catalyzed C-H acylation with aldehydes using tert-butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2-aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromat- ic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate-limiting electrophilic C-H cyclopalladation (k_H/k_D=3.6; ρ~+ = -0.74) to form an arylpalladium complex, followed by acyl radical functionalization.