A unified strategy for exceptionally high diastereoselectivity in the photochemical ring closure of chiral diarylethenes.

Into my arms: Photochemical cyclization of diarylethenes that have two chiral side arms showed up to 100% de (see scheme). Introduction of these chiral side arms onto the carbon atoms where ring closure occurs is a general strategy for the highly diastereoselective cyclization of diarylethenes.