PHOTOCHEMISTRY OF SOME 2,5-SUBSTITUTED TROPONE MESOGENS

The photoreactivity of three 2-acyloxy-5-alkoxytropone derivatives, tw o of which are known to show thermotropic liquid crystalline phases, h as been studied with the aim of finding photoresponsive mesogenic mate rials. The irradiation of solutions of these compounds in CH,CN under air atmosphere brings to endoperoxides which do not show mesomorphism and are not fully reversible to their respective precursors neither ph otochemically nor thermally. From the chemical point of view, the faci le and relatively neat formation of endoperoxides open synthetic route s to new functionalized tropone derivatives. (C) 1998 Elsevier Science S.A. All rights reserved.