Cycloaddition reactions of N-alkoxycarbonyl-4-quinolones

3-Ethoxycarbonyl-4-1(H)-quinolone (2) and 3-nitro-4-1(H)-quinlone (3) reacted with a variety of chloroformates to give the N-acyl-3-ethoxycarbonyl-4-1(H)-quinolones (4a-4d) and N-acyl-3-nitro-4-1(H)-quinolones (5a,b) respectively. Reaction of (4a,b,d) with 1-methoxy-3-(trimethylsilyloxy)-1,3-butadiene (6) gave the respective[4+2]cycloadduct,5,10a-diethoxycarbonyl-3,10-dioxo-1-methoxy-octahydroacridine(7a)and the analogues (7b,d). Treatment of (5a,b) with the above diene gave rise to two cycloadducts 3,10-dioxo-5-ethoxycarbonyl-1-methoxy-10a-nitro-octahydroacridines which had arisen from addition from the exo and endo transistion states. The quinolones (4a,b) on reaction with Gessons diene (12) and the ketene acetals (15) and (16), afforded Michael adducts 2-[1,3-biscarboethoxy-1,2-dihydroquinolin-2-yl-4-hydroxy]-methyl-1-carboethoxy-4-methoxycyclohexa-1,3-diene (14a), and (14b),(17),(18) respectively. Base treatment of (14a,b) gave the aminoketone 7-(2'-aminobenzoyl)-8-hydroxy-3-methoxy-1,2-dihydronaphthalene (19) which was acetylated to afford (20). The latter could be selectively O-deacetylated to give 7-(2'-acetamidobenzoyl)-8-hydroxy-3-methoxy-1,2-dihydronaphthalene (21). © 1989.