Azobenzene–based Chiral Photoswitchable Catalysts

Chiral photoswitchable catalysts can modulate reactivity and selectivity of enantioselective reaction by photoisomerization. While a variety of the catalysts have been developed due to their utility in the field of asymmetric synthesis, azobenzene, which is readily available and well–known photoresponsive unit, has rarely been applied to chiral photoswitchable catalysts. We have developed a variety of azobenzene–based chiral photoswitchable organocatalysts and ligand such as azobenzene BINOL crown ether (ABCE), azobenzene BINOL hybrid oligoethylene glycol (ABOEG), and azopyridine–oxazoline (AZOX). The (Z)–ABCE accelerated enantioselective alkylation of glycine Schiff base in comparison with the (E)–ABCE. The ABOEG changed reactivity and enantioselectivity in asymmetric amination of imines through photoisomerization. The AZOX also controlled enantioselectivity in asymmetric intermolecular cyclization of sulfonamide through the photomodulation of the coordination mode. © 2023 Society of Synthetic Organic Chemistry. All rights reserved.