Selective synthesis of α- and β-glycosides of N-acetyl galactosamine using rare earth metal triflates

Abstract

Structures containing galactose and GalNAc residues are specifically recognized by asialoglycoprotein receptors, allowing them to selectively internalize by hepatocytes for drug-targeting delivery. However, methods for direct synthesis of GalNAc glycosides are still challenging due to the poor participating group of 2-acetamido. Here, we develop a facile strategy to synthesize various GalNAc glycosides by employing a series of rare earth metal triflates, and the results demonstrate that both α-glycosides and β-glycosides of GalNAc can be obtained by conducting with Hf(OTf)4 and Sc(OTf)3, respectively. These applicable results indicate that any interested GalNAc-containing substrates could be prepared by this simple strategy.

Tumor-Targeted Oxaliplatin(IV) Prodrug Delivery Based on ROS-Regulated Cancer-Selective Glycan Labeling

“…Azidacetic acid was first generated from chloroacetic acid and sodium azide in sodium hydroxide solvent at 75 °C, which was conjugated with mannosamine hydrochloride and then followed with acetylation to form per-acetylated Ac 4 ManNAz (3). Finally, the desired metabolic precursor B−Ac 3 ManNAz was synthesized in one step from Ac 4 ManNAz in the presence of Sc(OTf) 3 and HBAPE with a yield of 61%, according to our previously optimized procedure 22 (Scheme 2). All the synthetic compounds were characterized by 1 H and 13 C NMR spectroscopy in Supporting Information and the purity of targeted B−Ac 3 ManNAz was further confirmed by HPLC.…”