title: A novel photochromic system of 4,5-dialkenylthiophenes constructed by the smarium diiodide promoted coupling reactions of thiophene-2-carboxylate with aryl ketones.
abstract: [reaction: see text] The SmI2-promoted coupling reaction of ethyl thiophene-2-carboxylate with aryl ketones (2 equiv), followed by acid-catalyzed dehydration and oxidative aromatization, gave dialkenylthiophenes 1b-d, which underwent electrocyclizations upon irradiation with 300-nm light in CH3CN solution to give the corresponding closed-ring species with absorption lambda(max) approximately 425 nm. The interconversion between dialkenylthiophenes and their corresponding closed-ring species constitutes a novel photochromic system bearing an ester group for potential uses in linkage and wavelength tuning.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, Republic of China.
authors.forename: Jiun-Jie
authors.initials: JJ
authors.lastname: Shie
authors.forename: Shyh-Ming
authors.initials: SM
authors.lastname: Yang
authors.forename: Chao-Tsen
authors.initials: CT
authors.lastname: Chen
authors.forename: Jim-Min
authors.initials: JM
authors.lastname: Fang