SYNTHESIS OF BENZO[C]CINNOLINE 5,6-DIOXIDES AND RELATED COMPOUNDS

The preparation of a variety of benzo[c]cinnolines as well as benzo[c]cinnoline monoxides and dioxides by reduction of the corresponding 2,2‐dinitrobiphenyls with hydrogen and Raney nickel of low activity is described. The detailed procedures developed produce superior yields of benzo[c]cinnoline monoxides and dioxides. The structure of some intensely‐colored red‐violet amino, alkylamino, and hydroxybenzo[c]cinnoline monoxides and dioxides is discussed and these are compared with the essentially colorless alkoxyl and acetylamino derivatives. The long wave length band in the U. V. spectrum of the colored compounds is compared. Copyright © 1969 Journal of Heterocyclic Chemistry