Palladium-Catalyzed Ortho-C-H Acylation Of2-Arylbenzoxazoles

2-Arylbenzoxazoles are the important biaryl pharmacophore with lower toxicities, which have exhibited a variety of biological activities, including anti-HIV, antiinflammatory, antimicrobial, antibiotic, and antitumor properties. Further extension and branching functional substituents on the benzoxazole skeleton would have valuable significance for the organic syntheses and pharmaceutical chemistry. This thesis reports Pd-catalyzed ortho-C-H acylation of2-arylbenzoxazoles, affording the desired products in moderate to excellent yields. Various arylbenzoxazoles and aldehydes could be conducted under the optimized reaction conditions, using Pd(OAc)2as the catalyst, PPh3as the ligand, tert-butyl hydroperoxide (TBHP) as the oxidant, chlorobenzene as the solvent. Using benzoxazole as the directing group, this acylation occurs at the less sterically hindered ortho-C-H of the directing group, when the substrates contain a meta-substituent.