Photoswitchable Chiral Cation-Binding Catalyst: Photocontrol of Catalytic Activity on Enantioselective Aminal Synthesis.

Design of a suitable photoswitchable chiral cation-binding cage for the synthesis of optically active aminals was established using the azobenzene-BINOL hybrid oligoethylene glycol (ABOEG) through E/Z isomerization of the azobenzene unit. Under photoirradiation, both the catalytic activity and enantioselectivity of the generating (Z)-ABOEG are enhanced, in contrast to that of (E)-ABOEG, which can be attributed to the geometrically distinct coordination behavior between the metal cation and the oligoethylene glycols.