condensation of acetophenones with o-phenylenediamines and sulfur in DMSO in the
presence of piperidine as a catalyst. The products could be readily isolated from the reaction
mixture by simple precipitation and washing with methanol. This set of reaction conditions
applied to higher homologs of acetophenones as well as benzyl phenyl ketones led to 2, 3-
di-C-substituted quinoxalines. Further functionalization of 3-phenylquinoxaline-2-thione via …