Persulfate-promoted oxidative C-N bond coupling of quinoxalinones and NH-sulfoximines.

The persulfate-meditated oxidative C-N bond coupling of the C-H bond of quinoxalinones and the N-H bond of NH-sulfoximines is reported. The reaction proceeds smoothly under transition metal-free conditions and provides good to excellent yields of sulfoximidoyl-functionalized quinoxalinone products under mild conditions. The optimized conditions were found to be suitable for a range of sulfoximine and quinoxalinone substrates. This reaction offers a new and convenient strategy to directly install the sulfoximine moiety into the C3 position of quinoxalinone.

DABCO-catalyzed silver-promoted direct thiolation of pyrazolones with diaryl disulfides.

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.

Copper-catalyzed oxidative decarboxylative coupling of α-keto acids and sulfoximines.

A copper-catalyzed oxidative decarboxylative coupling of α-keto acids with NH-sulfoximines has been developed. With CuBr as the catalyst and K2S2O8 as the oxidant, this reaction enables the formation of a C-N bond and gives N-aroylsulfoximine products in moderate to excellent yields. The reaction mechanism is likely to involve the generation of a reactive aroyl radical intermediate.