Photochromic C2-Symmetric Chiral Diarylethene: From the Initial State to the Final State

• Published in: Journal of organic chemistry Vol. 77; no. 4; pp. 1853 - 1859
• Main Authors: Delbaere, Stéphanie, Berthet, Jérôme, Shiozawa, Tatsuya, Yokoyama, Yasushi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 17-02-2012
• Subjects: Alicyclic compounds; Alicyclic compounds, terpenoids, prostaglandins, steroids; Chemical Sciences; Chemistry; Exact sciences and technology; Heterocyclic compounds; Heterocyclic compounds with o, s, se, te hetero atom and condensed derivatives; or physical chemistry; Organic chemistry; Preparations and properties; Theoretical and; Cyclopentene derivative; Chemical rearrangement; Photochromism; Chiral compound; NMR spectrometry; Thermal reaction; Diastereoselectivity; Benzothiophene derivatives; Sulfur heterocycle; Cyclization; Ultraviolet irradiation; Photoinduction; Photochrome; By product; Diastereomer; Conformation; Dyes; Organic Pigments; Fluorescent Brighteners; Photographic Sensitizers
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo202466g

The behavior of 1,2-bis­[(R)-2-(1-methoxymethoxyethyl)-3-benzo­[b]­thienyl] hexafluorocyclopentene before and upon UV irradiation and during thermal evolution of the photoirradiated solution has been thoroughly investigated by multinuclear NMR spectroscopy. A dynamic NMR study of the initial state was performed, providing a detailed description of the perceived conformational processes in the system. Before irradiation, three open conformations are in equilibrium, whereas UV irradiation generated the two expected cyclized diastereomers. The minor diastereomer was thermally less stable than the major one, thus leading to an unexpected increase in the diastereoselectivity when raising the photoirradiation temperature. In addition, a long thermal evolution induced slow rearrangement of the stable diastereomer into byproducts that were identified.