Approaches to Pyranuronic β-Sugar Amino Acid Building Blocks of Peptidosaccharide Foldamers

Pyranuronic β-sugar amino acids (β-SAAs) are biocompatible and tuneable building blocks of foldamers and chimera-peptides. The scalable and economical total synthesis of two building blocks is described here. These C-4 epimers, Fmoc-GlcAPU(Me)-OH (7) and Fmoc-GalAPU(Me)-OH (8), which are suitable for solid phase peptide synthesis, were prepared via a common oxime intermediate 16. The new synthesis uses nine consecutive steps, starting from methyl α-d-glucopyranoside (6). The synthesis is fine-tuned, optimized, and ready for large-scale and cost-efficient production