| Popis: |
In one of our previous papers in the series on the photochemistry of heteroaryl substituted o-divinylbenzenes (1) we demonstrated the first example of the photochemical synthesis of [3.2.1] bicyclic compounds (2) by intramolecular cycloaddition of b-(2-furyl)-o-divinylbenzenes (1, R = 2-furyl). In comparison to the photochemical behaviour of b-aryl-o-divinylbenzenes (1, R = phenyl) which undergo [2+2] cycloaddition and formation of the benzobicyclo[2.1.1]hexene derivative (3) b-(2-furyl)-o-divinylbenzenes (1, R = 2-furyl) is the sole system in which the b- substituent is involved in the intramolecular cycloaddition giving bicyclo[3.2.1]octadiene derivative (2), in very good yield. Thus, it was of considerable interest from mechanistic and synthetic points of view, to study the photochemical behaviour of furan derivatives in which the furan ring is a part of the condensed systems in order to obtain the polycyclic structures. This work reports about the photochemical reactions of o-vinylstyryl derivatives of benzofuran, naphtho[2, 1-b]- and naphtho[1, 2-b]furan (4). The structure determination of the products as well as the mechanism of the reactions will be discussed. |
