Phenanthro[4,5-bcd]furan Derivatives. V. The Cyclization of (Dibenzofuran-1-yl)acetic Acid Derivatives
摘要:
The cyclization of (6-methoxy-1,2,3,4-tetrahydrodibenzofuran-1-yl)acetic acid (3b) and (6-methoxy-1,2,3,4,4a,9b-hexahydrodibenzofuran-1-yl)acetic acid (5) to the corresponding phenanthro[4,5-bcd]furans have been examined. The cyclization of 3b was difficult, while that of 5 was easy. The difficult cyclization of 3b has been attributed to strains in the reaction intermediate.