Au(III) catalyst supported on a thermoresponsive hydrogel and its application to the A-3 coupling reaction in water

Abstract

Poly(NIPAM-co-4-VP), synthesized from N-isopropylacrylamide and 4-vinylpyridine with a 1:1 monomer ratio, exhibits a temperature-dependent phase transition in water with a low critical solution temperature (LCST) of 47°C. Coordination of Au(III) with the polymer results in material with metal catalytic activity combined with the inverse solubility phenomenon of the polymer, which catalyzes the three-component coupling reaction of aldehydes, amines, and alkynes in water with excellent yields. The polymer not only functions as a supporter for Au(III) but also accelerates the catalysis by undergoing a coil-to-globule phase transition above the LCST. The catalyst is efficient, is stable in air, and tolerates a variety of substrates. Moreover, the recyclability of the catalyst makes it eco-friendly and economical to use.