Synthesis and Photochromic Properties of Cycloalkylidene Fulgides

A series of cycloalkylidene fulgides have been synthesized using (beta),(gamma)-unsaturated diesters, instead of the usual a,P-unsaturated diesters. A study of their photochromic properties revealed that an increase in the cycloalkylidene ring size caused a subsequent decrease in the formation of the closed form from the open form.