Palladium-catalyzed multi-acetoxylation of 1,3-disubstituted 1H-pyrazole-5-carboxylates via direct C(sp2)H or C(sp3)H bond activation

A palladium-catalyzed mono- to tri-acetoxylation of 1,3-disubstituted 1H-pyrazole-5-carboxylate derivatives is described, with special attention focused on the investigation of the sequence of this process and the observation of the preference with regard to the activation of C(sp3)H bond over that of C(sp2)H bond.