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

[Image: see text] 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.