Efficient syntheses of ‘ellipticine quinone’ and the other three isomeric 5H-pyrido[x,y-b]carbazole-5,11(6H)-diones
Abstract
6H-Pyrido[x′,y′ : 5,6]oxepino[3,2-b]indol-5-(12H)-ones (3) are efficiently converted by hot alcoholic base in air into the corresponding 5H-pyrido[x,y-b]-carbazole-5,11(6H)-diones (5).