180° Unidirectional Bond Rotation in a Biaryl Lactone Artificial Molecular Motor Prototype

A bifunctional biaryl lactone has been synthesized that should be capable of iterative unidirectional aryl−aryl bond rotation via:  (1) a diastereoselective lactone ring opening, (S)-1 to (P,S)-2 or (M,S)-2; (2) a chemoselective lactonization, (P,S)-2 or (M,S)-2 to (S)-3; and (3) a chemoselective hydrolysis, (S)-3 to (S)-1. Preliminary results of a racemic sample have indicated unidirectional 180° rotation with very high directional selectivity per individual artificial molecular motor molecule through the first two steps of this sequence.