Switchable Site‐Selectivite Direct Acetoxylation of Pyrazolones

Abstract Site‐selective direct acetoxylation of pyrazolones was accomplished by utilizing an easy‐to‐handle (diacetoxyiodo)benzene (PIDA) as the sole acetoxylating reagent. In the presence of Pd(OAc) 2 catalyst, the 4‐acetoxylated pyrazolone product was exclusively formed. Meanwhile, in the absence of Pd(OAc) 2 , the pyrazolone methyl acetate product was obtained over the C sp 2 −H bond functionalization. Both approaches have been successfully applied to various pyrazolone substrates, giving the corresponding products in moderate to high yields under mild conditions.