抄録
Intramolecular cycloaddition of N-allyl-4-methyloxazole-5-carboxamides (1) gave the corresponding 6a-acetyl-2-hydroxy-6-oxotetrahydrofuro [2, 3-c] pyrrolidines (3). Tricycloadducts (6) were obtained by the intramolecular Diels-Alder reaction of N-(3-butenyl)-4-methyl-N-phenyloxazole-5-carboxamides (4). Hydrolysis of the tricycloadducts (6) afforded 7a-acetyl-2-hydroxy-7-oxo-6-phenyl-tetrahydrofuro [2, 3-c] piperidines (8). Treatment of the tricycloadducts (6) with acetic acid gave 1, 2, 3, 4-tetrahydroisoquinolin-1-ones (10), 8a-hydroxy-1, 2, 3, 4, 5, 6-hexahydroisoquinoline-1, 6-diones (9') and 8a-hydroxy-1, 2, 3, 4, 5, 8-hexahydroisoquinoline-1, 8-diones (9). Similar intramolecular cycloaddition of alkenyl 4-methyloxazole-5-carbamates (11) is also described.
