Synthesis of some pyrazino, pyrimido and mercaptopyrimido annelated carbazoles using 2 -hydroxymethylene -1 -oxo -1,2,3,4 -tetrahydrocarbazoles

Treatment of l-oxo-2-hydroxymethylene-l,2,3,4-tetrahydrocarbazole 1 with hydrazine hydrate, hydroxylamine hydrochloride, urea and thiourea in the presence of gl. acetic acid afforded the novel carbazole derivatives namely 4,5-dihydro-2H-pyrazino [3,4-a]carbazoles 2, 2-cyano-1-hydroxycarbazoles 3, 2,4-dihydroxy-1,4,5,6-tetrahydro-pyrimido[4,5-a]carbazoles 4 and 4-hydroxy-2-mercapto-1,4,5,6-tetrahydropyrimido-[4,5-a]carbazoles 5 respectively.