Quinoxalines are class of compounds important as core for various biological activities. The general methodology involves coupling or condensation of o-phenylenediamines with diketones.
Recently, Baohua Chen and co-workers reported interesting synthesis of Cu-catalyzed quinoxalines synthesis from nitroolefins and o-phenylenediamines.
In the optimization study, catalysts including CuBr2, Cu(OAc)2, CuO were screened under various conditions of solvents and temperature and (E)-(2-nitroprop-1-en-1-yl)benzene
and o-phenylenediamine were chosen as model substrates. The best results were obtained using 10 mol% of CuBr2 as catalyst in ethanol as a solvent at 110 °C, to give the 90% yield of desired quinoxaline deri. after column purification. Later, the optimized condition was extended for the substrate suitability reactions to give the yield of desired products in moderate to good yields depending on the EWG and EDG on diamine part or nitroolefin part.
The group has proposed a mechanism were the nitro-group plays a key role in the reaction.
Overall, a new, different and good process for the synthesis of quinoxaline deri. considering the availability and easier acess to nitroolefins by one step synthesis and o-phenylenediamines.
Recently, Baohua Chen and co-workers reported interesting synthesis of Cu-catalyzed quinoxalines synthesis from nitroolefins and o-phenylenediamines.
In the optimization study, catalysts including CuBr2, Cu(OAc)2, CuO were screened under various conditions of solvents and temperature and (E)-(2-nitroprop-1-en-1-yl)benzene
and o-phenylenediamine were chosen as model substrates. The best results were obtained using 10 mol% of CuBr2 as catalyst in ethanol as a solvent at 110 °C, to give the 90% yield of desired quinoxaline deri. after column purification. Later, the optimized condition was extended for the substrate suitability reactions to give the yield of desired products in moderate to good yields depending on the EWG and EDG on diamine part or nitroolefin part.
The group has proposed a mechanism were the nitro-group plays a key role in the reaction.
Overall, a new, different and good process for the synthesis of quinoxaline deri. considering the availability and easier acess to nitroolefins by one step synthesis and o-phenylenediamines.
