Unusual [2 + 2] topochemical cycloadditions of 3-cyano- and 4-cyano-cinnamic acids: temperature dependent solid state photochemical reactions
Abstract
The seeming difference in the topochemical [2 + 2] photoreactivity of 3-cyanocinnamic acid 1 and 4-cyanocinnamic acid 2 is caused by differing degrees of ease of molecular motion in the crystals and the unreactive 1 becomes reactive when heated to 130 °C.