Oxidation of alkynes using PdCl2/CuCl2 in PEG as a recyclable catalytic system: one-pot synthesis of quinoxalines

Alkynes were oxidized efficiently using the catalytic amount of PdCl2 and CuCl2 in PEG-400 in the presence of water, providing excellent yields of the corresponding 1,2-diketones. A variety of alkynes were well-suited substrates for the oxidation under the described conditions. Further, the optimized conditions were successfully utilized for the one-pot synthesis of 2,3-disubstituted quinoxaline derivatives.