Synthesis of substituted pyrazolo[1,5-a]quinoxalines using the reductive cyclization

New pyrazolo[1,5-a]quinoxalin-4-ones were obtained by reductive cyclization from the corresponding 1-(2-nitroaryl)pyrazole-5-carboxylates. Alternatively, pyrazolo[1,5-a]quinoxalines were prepared from N-hydroxypyrazolo[1,5-a]quinoxalines.