Thermoresponsive Starch Hydrogel Stabilized Pd Nanoparticles: Soft Catalyst for the Preparation of (±)-α-Methylbiphenylalanine in Water Aiming at Bioorthogonal Chemistries

Abstract

The corn-starch was able to reduce Pd(II) species under relatively low concentration (5.0 wt/vol) leading to the formation of a thermoresponsive palladium nanoparticles-containing hydrogel with D = 16.1 nm ± 6.4 nm. It was successfully applied to the Suzuki–Miyaura reaction step in neat water involved in the synthesis of (±)-N-acetyl-α-methyl-4-biphenylalanine ethyl ester, a direct precursor of an unnatural quaternary biarylalanine.