We report the syntheses
of 1,3,4-tri-O-acetyl-2-amino-2,6-dideoxy-β-d-glucopyranose and allyl 2-amino-2,6-dideoxy-β-d-glucopyranoside fromd-glucosamine hydrochloride. The potential
of these two versatile scaffolds as key intermediates to a diversity
of orthogonally protected rare deoxyamino hexopyranosides is exemplified
in the context of fucosamine, quinovosamine, and bacillosamine. The
critical C-6 deoxygenation step to 2,6-dideoxy aminosugars is performed
at an early stage on a precursor featuring an imine moiety or a trifluoroacetamide
moiety in place of the 2-amino group, respectively. Robustness and
scalability are demonstrated for a combination of protecting groups
and incremental chemical modifications that sheds light on the promise
of the yet unreported allyl 2,6-dideoxy-2-N-trifluoroacetyl-β-d-glucopyranoside when addressing the feasibility of synthetic
zwitterionic oligosaccharides. In particular, allyl 3-O-acetyl-4-azido-2,4,6-trideoxy-2-trifluoroacetamido-β-d-galactopyranoside, an advanced 2-acetamido-4-amino-2,4,6-trideoxy-d-galactopyranose building block, was achieved on the 30 g scale
from 1,3,4,6-tetra-O-acetyl-β-d-glucosamine
hydrochloride in 50% yield and nine steps, albeit only two chromatography
purifications.