Condensed isoquinolines 26. Oxidation reactions of 6,11-dihydro-13H-isoquino-[3,2-b]quinazolin-13-one derivatives

Oxidation of the hydrobromide of 6,11-dihydro-13H-isoquino[3,2-b]quinazolin-13-one with dimethyl sulfoxide leads to 11-hydroxy-11H-isoquino[3,2-b]quinazoline-6,13-dione, and with hydrogen peroxide to the hydrobromide of 2-[(4-oxo-3,4-dihydro-2-quinazolinyl)carbonyl]benzoic acid. Salts of 5-and 6-alkyl-substituted isoquino[3,2-b]quinazolines are readily oxidized on boiling in nitrobenzene, which leads to aromatization of the isoquino[3,2-b]quinazoline system to 5-methyl-13-oxo-5H,13H-isoquino[ 3,2-b]quinazolinium perchlorate and 6-benzyl-13H-isoquino[3,2-b]quinazolin-13-one. The structures of the dehydrogenation products were established from ¹H NMR and UV spectra. The interaction of the obtained compounds with NaBH₄ has been studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1833–1840, December, 2007.