4-Cinnolinecarboxylic acid 1-oxide

Ammo-4-cinnolinecarboxylic acid 1-oxide (40) with acetic anhydride gave 3-methyl-l//-[l,3]oxazino[4,5-c]cinnolin-l-one (41) (neat AC2O, reflux, h 96%). ... 

Amino-4-cinnolinecarboxylic acid 1-oxide (17) gave 3-cumoIinamine (18) (Na2S204, Me2NCHO, H2O, reflux no further details). " ... 

Cinnolinecarboxylic acid 4-Cinnolinecarboxylic acid 1-oxide 4-Cinnolinecarboxylic acid 2-oxide... 

Other 1,2-diazines synthesized included 4-amino-3-cinnolinecarboxylic acids <97PHA91 >, I -aryl-6-chloro-l,4-dihydro-4-oxothieno[2,3-c]pyridazine-3-carboxylic acids <97JPR284>, 2H-benzo[2,3-g]pyridazino[4,5-<7,e]quinolin-3-ones <97M681>, 3-chloro-4-carbamoyl-5-aryl-6-methylpyridazine N-oxides <97F67>, 2-aroyl-6-(hetero substituted)-3(2//)-pyridazinones <97HCM267>, and 5-(4-hydroxycinnolin-3-yl)tetrazoles 2-methyl-5-(4-acetoxycinnolin-3-yl)-... 

The formation of cinnolinecarboxylic acids by primary synthesis (see Chapter 1) and by hydrolysis of trihalogenomethylcinnolines (see Section 3.2) have been covered already the oxidative routes from alkylcinnolines, hydroxyalkylcinnolines, or cinnolinecarbaldehydes appear to be unrepresented in the 1972-2004 literature the remaining approaches are illustrated in the following classified examples. 

Note. These reactions of acylcinnolines have been covered already reduction to alkylcinnolines (Section 2.2.1), some cyclocondensations (Section 4.1.2.2), and reduction to extranuclear hydroxycinnolines (Section 4.2). Their oxidation to cinnolinecarboxylic acids appears to be unrepresented in the more recent literature. Some other reactions are illustrated in the examples that follow. 

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