A facile and efficient oxidative CÀH acylation of N-substituted pyrazolones using a-oxocarboxylic acids as an acyl group source was developed. A combination of Cu(OAc) 2 and K 2 S 2 O 8 enables the reaction to proceed smoothly under air and provides a wide array of 4-acylpyrazolone products in moderate to excellent yields. The mechanism of this transformation is believed to proceed via a copper-induced decarboxylation to form the acyl-copper species. This method provides a convenient and useful route for a direct installation of an acyl moiety into bioactive pyrazolone derivatives, which can be further utilized in many applications.

A highly efficient protocol for a direct thiolation of N-substituted pyrazolones with diaryl disulfides is described. Using a combination of DABCO and silver(i) acetate, the C-S bond formation proceeds smoothly at room temperature under mild and easy to handle conditions. This synthetic strategy offers a convenient and direct modification of antipyrine and other pyrazolone substrates, giving a series of aryl sulfide-substituted pyrazolone products in moderate to excellent yields.