Chiral Discrimination in Photochromic Helicenes

Abstract
A photoresponsive dithienylethene derivative bearing chiral pinene-based arms underwent a stereoselective photoinduced cyclization reaction to produce greater than 98% of a single diastereomer. The magnitude of the optical rotation changed as much as Delta[alpha]373 = 8698 degrees upon alternate irradiation with 400 nm and greater than 434 nm light.