Force-Triggered Atropisomerization of a Parallel Diarylethene to Its Antiparallel Diastereomers.

This paper describes a mechanical approach to inducing the atropisomerization of a parallel diarylethene into its antiparallel diastereomers exhibiting distinct chemical reactivity. A congested parallel diarylethene mechanophore in the ( R a ,S a )-configuration with mirror symmetry is atropisomerized to its antiparallel diastereomers with C 2 symmetry under ultrasound-induced force field. The resulting stereochemistry-converted material gains symmetry-allowed reactivity toward conrotatory photocyclization.