DDQ: the chlorinating reagent and oxidant for the ligand-directed ortho-chlorination of 2-arylpyridines

Abstract

A new and simple protocol for palladium-catalyzed ligand-directed ortho-chlorination of 2-arylpyridines with DDQ was developed, generating the chlorinated products in good to excellent yields. Note that DDQ played dual roles as both the chlorinating reagent and oxidant in this reaction. Moreover, high regioselectivity was observed for 2-arylpyridines bearing a meta-substituent in the aryl ring moiety, and the chlorination could take place at the less sterically hindered ortho-C–H bond.