ring on the other end of the double bond were synthesized in an attempt to get thermally irreversible photochromic compounds having absorption bands at longer wavelengths. 2-(1,2-Dimethyl-3-indolyl)-3-(2,4,5-trimethyl-3-thienyl)maleicanhydride(8a) underwent photoinduced cyclization/ring-opening reactions with relatively high quantum yields (cyclization quantum yield: 0.15; ring-opening quantum yield: