Diastereoselective cyclization of a diarylethene having a chiral N-phenylethylamide substituent in crystals

A diarylethene which has an N-phenylethylcarbamoyl substituent at the periphery of 1,2-bis(2-methyl-5-phenyl-3-thienyl)hexafluorocyclopentene was synthesized. The diarylethene underwent a photochromic reaction both in solution and in the single-crystalline phase. The chiral substituent at the end of the molecule contributed to the intermolecular hydrogen bond formation in the crystal and the crystal adopted the chiral space group P21. In the crystalline phase photocyclization reaction, only one closed-ring diastereomer was produced, while the diastereoselection was not observed in solution.