A Novel Photochromic System of 4,5-Dialkenylthiophenes Constructed by the Samarium Diiodide Promoted Coupling Reactions of Thiophene-2-carboxylate with Aryl Ketones
摘要:
[GRAPHICS]The Sml(2)-promoted coupling reaction of ethyl thiophene-2-carboxylate with aryl ketones (2 equiv), followed by acid-catalyzed dehydration and oxidative aromatization, gave dialkenylthlophenes 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) approximate to 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.