Photochromism of dihydroindolizines. Part XVIII: Palladium-catalyzed Negishi coupling for the synthesis of photochromic dihydro 5-azaindolizine- linker-conjugates with a terminal ethylene anchoring group

Abstract

Eight new photochromic dihydro 5-azaindolizine-linker-conjugates with a terminal ethylene anchoring group have been synthesized via palladium-catalyzed Negishi coupling. Polychromatic light irradiation of the photochromic dihydro 5-azaindolizines (DHAIs) led to ring-opened colored betaines which underwent reversible thermal 1,5-electrocyclization into their corresponding DHAIs in the second domain. The noteworthy multiaddressable photochromic properties are useful for a plethora of new applications for these materials such as anchoring the ethylene group to metal-oxide nanoparticles. © 2012 Elsevier Ltd. All rights reserved.