Novel sulfoxide-introducing reaction and photochromic reactions of ethenylsulfinyl derivatives of dithienylethenes

New diarylethenes possessing one or two arenesulfinylethenyl moieties were casually synthesised. The photochromic and chiroptical properties of 1,2-bis-2-{2-methyl-5-[2-(4-toluenesulfinyl)ethenyl]-3-thienyl}-3,3,4,4,5,5-hexafluorocyclopentene were examined. While its colouring quantum yield by 313-nm irradiation (ΦO→C) was as large as 0.46, its bleaching quantum yield by 621-nm irradiation (ΦO→C) was negligibly small. Diels–Alder reaction of 2-(4-toluenesulfinyl)-1,4-benzoquinone with diarylethenes with the structure of 1-aryl-2-(5-ethenyl-2-methyl-3-thienyl)-3,3,4,4,5,5-hexafluorocyclopentene gave, instead of the expected Diels–Alder cycloadduct or its derivatives, 1-aryl-2-{2-methyl-5-[2-(4-toluenesulfinyl)ethenyl]-3-thienyl}-3,3,4,4,5,5-hexafluorocyclopentene.