Quinoxalino[2,3- c ]cinnolines and their 5- N -oxide: Alkoxylation of methyl-substituted quinoxalino[2,3- c ]cinnolines to acetals and orthoesters

We report the alkoxylation of methyl-substituted quinoxalino[2,3-c] cinnolines to give acetals and orthoesters in high yields. Routes to the precursors of this alkoxylation reaction as well as other quinoxalino[2,3-c] cinnoline and their 5-oxide derivatives are reported. Most of these quinoxalino[2,3-c]cinnolines were prepared by cyclization of the corresponding 2-amino-3-(2-nitrophenyl)quinoxaline, which, in turn, result from an unusual Beirut reaction from benzofurazan oxides plus 2-nitrobenzylcyanides. Mechanistic explanations for these intriguing reactions are presented.