Lactone-Facilitated Chemoenzymatic Synthesis of Sulfoglucuronosyl Paragloboside Oligosaccharides Bearing the HNK-1 Epitope

Herein, we describe a lactone-facilitated chemoenzymatic strategy for the synthesis of sulfoglucuronosyl paragloboside pentasaccharide, sulfoglucuronosyl lactosaminylparagloboside heptasaccharide, and their nonsulfated derivatives. The approach involves the efficient enzymatic modular assembly (EMA) of the nonsulfated paragloboside backbones, followed by highly regioselective chemical manipulation steps that introduce a sulfate group at the C3 position of glucuronic acid through the formation of a C6,3-lactone intermediate.