Synthesis of 12,13-dihydro-5-oxoquinolino[2,3-a]carbazoles,3,11-dihydro-2,4-dioxopyrano[2,3-a]carbazoles and quinolino[2,3-b]carbazolo[6,5-a]pyran-7,8-diones

摘要

The reaction of 1-hydroxycarbazoles la-d with anthranilic acid in the presence of fused zinc chloride and phosphorus oxychloride at room temperature affords 1,7-dibenzoazocin-6,12-dione 2 in all the cases and the expected 12,13 dihydro-5-oxoquinolino[2,3-a]carbazoles 3a-d.In another reaction,1-hydroxycarbazoles la-d with malonic acid in the presence of fused zinc chloride and phosphorus oxychloride at room temperature yields 3,11-dihydro-2,4-dioxopyrano[2,3-a]carbazoles 4a-d.Further,the attempted synthesis of c/b fused quinolinodipyrano annelated carbazoles 7a-d or 8a-d or both from the reaction of 3,1 1-dihydro-2,4-dioxopyrano[2,3-a]carbazoles 4a-d with vinyl acetate and 2,4-dihydroxyquinoline 6 results in the formation of new dimerised product,quinolino[2,3-6]carbazolo[6,5-a]pyran-7,8-diones 9a-d.A plausible mechanism has been suggested to explain this reaction.