| abstract |
A fulgimide derivative of the formula: ##STR1## wherein R 1 , R 2 , R 3 are independently alkyl cycloalkyl aryl etc.; R 4 is thienyl, indolyl, furyl, etc.; X is a divalent organic residue; and R is amino, OH, etc., or a vinyl group, has a photochromic action and can be used for producing photochromic polymers and copolymers. |