Synthesis of Conjugated Spiropyran Dyes via Palladium-Catalyzed Coupling Reaction

Abstract
Spiropyrans (5a-h) conjugated at 6 position have been conveniently and efficiently prepared by palladium-catalyzed coupling of 6-iodospiropyran (4a, 4b) with olefins or alkynes in moderate to high yield. This method might be a particularly very important way as one of structural modifications for further study of spiropyran containing liquid crystals, which might be a potential optical switch (LCOS) development based on the principle of photoresolution.