Reaction of Heteroaromatic Analogs of Homophthalic Anhydride

The reactions of heterohomophthalic anhydrides, 3-carboxy-1-methylindole-2-acetic anhydride (4), 2-carboxybenzo [b] furan-3-acetic anhydride (5), 2-carboxythiophene-3-acetic anhydride (6), and 3-carboxy-1, 4-dimethylpyrrole-2-acetic anhydride (23) with carbon-carbon multiple bonds (C=C and C≡C), acylating agents, and cyclic imines are described. Treatment of the anhydrides (4-6) with various compounds containing carbon-carbon multiple bonds (7-10) in the presence of a strong base caused cycloaddition with spontaneous extrusion of carbon dioxide to give the corresponding linearly condensed peri-hydroxy heteroaromatic compounds (11-19), regioselectively. Base-catalyzed acylation of 4 with acetic anhydride and β, β-dimethylacryloyl chloride gave 3, 5-dimethylpyrano [4, 3-b] indol-1 (5H)-one (21) and 3, 3, 11-trimethyl-3, 4-dihydropyrano [4', 3' : 2, 3]-pyrano [4, 5-b] indole-1, 6 (11H)-dione (22), respectively. Reaction of the anhydrides (4, 6, and 23) with 3, 4-dihydroisoquinoline (24) gave the corresponding condensation products, 14-carboxy-13-methyl-5, 6, 14, 14a-tetrahydrobenz [a] indolo [3, 2-g] quinolizin-8 (13H)-one (25), 12-carboxy-5, 6, 12, -12a-tetrahydrobenzo [a] thieno [2, 3-g] quinolizin-8-one (26) and 12-carboxy-11-methyl-5, 6, 12, 12a-tetrahydrobenzo [a] pyrrolo [3, 2-g] quinolizin-8 (11H)-one (27), in high yields.