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An efficient microwave assisted protocol for the synthesis of Mannich’s bases of isatoic-anhydride derivatives 4(a-g) has been described. Treatment of isatoic anhydride (1) with formaldehyde yielded 1-hydroxymethyl-1Hbenzo[ d][1,3]oxazine-2,4-dione (2) followed by reaction with HCl afforded 1-chloromethyl-1H-benzo[d][1,3]oxazine- 2,4dione (3) which reacted smoothly with sec. amines to give mannich’s bases 4(a-g) in excellent yield.
Application of the Japp-Klingemann reaction on N-substituted-(3-hydroxymethylidine)-piperidin-4-one 6(a-d) with 4- indophenazine diazonium chloride (5) and 5-indophenazine diazonium chloride (9) yielded the corresponding 3-(4- indophenazinyl)-hydrazone of N-substituted piperidin-4-ones 7(a-d) and 3-(5-indophenazinyl)-hydrazone of Nsubstituted piperidin-4-ones 10(a-d) respectively. Fischer indolization of 7(a-d) and 10(a-d) hydrazones with Kent’s reagent (4:1 mixture of acetic acid:HCl) afforded N-substituted-2,3-dihydro-14H-azacarbazolo(2,3-b)-pyrazino(2,3-b)- 11H-indole-1-ones 8(a-d) and N-substituted-2,3-dihydro-14H-azacarbazolo(2,3-b)-6H-pyrrolo (3,2-b)-quinoxaline-1- ones 11(a-d) in moderate to good yield. All azacarbazole derivatives 8(a-d) and 11(a-d) were characterized on the basis of their microanalysis, IR, 1H NMR and MS spectral data.
