Intramolecular Photocycloaddition of Stilbazoles Tethered by Silyl Chains

摘要

Photophysical properties and photochemical reactions of stilbazoles and stilbazolium salts have been extensively studied so far. As for the photochemical reactions of stilbazoles and stilbazolium salts, three types of photochemical reactions are known. Those are (1) photodimerization, (2) cis-trans photoisomerization, and (3) photocyclization to azaphenanthrenes via oxidative dehydrogenation. Among them, photodimerization of stilbazoles is not an efficient process even in high concentration. Recently, we reported similar three types of photochemical reactions of stilbenes can be controlled by tethering two stilbene units by silyl chains. In this work, to control the photoreactions of stilbazoles, photoreactions of silyl-tethered stilbazoles were investigated. Particularly, to increase the efficiency and stereoselectivity of photocycloaddition of stilbazoles, effects of additives were studied.