56156-75-3Relevant academic research and scientific papers
o-Nitrobenzylidene Compounds. Part 3. Formation of 4-Arylamino-3-methoxycinnoline 1-Oxides from N-o-Nitrobenzylideneanilines, Cyanide Ion, and Methanol: the Intermediacy of 2-Aryl-3-cyano-2H-indazole 1-Oxides
Johnston, David,Smith, David M.,Shepherd, Thomas,Thompson, David
, p. 495 - 500 (2007/10/02)
The N-o-nitrobenzylidene derivatives of variously substituted anilines (7) have been cyclised by potassium cyanide in methanol, to give 4-arylamino-3-methoxycinnoline 1-oxides (9), the structures of which have been confirmed by independent synthesis of one representative .These cinnoline oxides are the main products (sometimes the only isolated products) when the amine-derived ring in (7) is ortho-substituted; in other cases the cinnoline oxides are minor products formed along with 2-aryl-3-cyano-2H-indazoles (10).In the latter group of reactions, the primary cyclisation products are 2-aryl-3-cyano-2H-indazole 1-oxides (8): these have then either been reduced to the indazoles in the basic methanolic medium, or have undergone ring-opening and recyclisation to give the cinnoline oxides (9).In the other group, where indazole oxides (8) cannot usually be isolated, their intermediacy in cinnoline oxide formation remains a possibility, although other mechanistic pathways can be envisaged.Some 'borderline' cases are identified and discussed.
