On the chemistry of cinnoline I. Synthesis and reactions of (4-amino-cinnolin-3-yl)-p-tolylmethanones

The synthesis of a series of (4-Amino-cinnolin-3-yl)-p-tolyl-methanones fro m aryl-hydrazonomalononitrile in a one step procedure is reported. The (4-a mino-cinnolin-3-yl)-p-tolyl- methanones could be annelated to the correspon ding 1,2-dihydro-4-(p-tolyl)-2-oxopyrido[3,2-c]cinnoline derivatives via (4 -acetamido-cinnolin-3-yl)-p-tolyl-methanones. Treatment of 1,2-dihydro-9-me thyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline-2-one with POCl3 and P2S5 gave 2-ch loro-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cinnoline. and 1,2-dihydro-9-methyl- 4-(p-tolyl)-pyrido[3,2-c]cinnoline-2-thione. Treatment of the ketone with m alononitrile afforded 2-amino-3-cyano-9-methyl-4-(p-tolyl)-pyrido[3,2-c]cin noline. Using these ketones, a facile and convenient route towards substitu ted pyrimidino[5,4-c]-cinnolines was developed. Chemical and spectroscopic evidences for the structures of the new compounds are presented.