Structural comparison of trehalose anomers; the X-ray crystal structures of αα-(2,3,4-tri-0-methyl-6-methanesulphonyl)glucopyranosyl-1-0-(2' 3' 4'-tri-o-methyl-6'- methanesulphonyl)glucopyranose, and its ββ-isomer

The crystal structures of 3-O-benzyl-1,2-O-iso-propyl-idene-5-O-methane-sulfonyl-6-O-tri-phenyl-methyl-α-d-gluco-furan-ose and its azide displacement product

The effect of different leaving groups on the substitution versus elimination outcomes with C-5 d-glucose derivatives was investigated. The stereochemical configurations of 3-O-benzyl-1,2-O-iso-propyl-idene-5-O-methane-sulfonyl-6-O-tri-phenyl-methyl-α-d-gluco-furan-ose, C36H38O8S (3) [systematic name: 1-[(3aR,5R,6S,6aR)-6-benz-yloxy-2,2-di-methyl-tetra-hydro-furo[2,3-d][1,3]dioxol-5-yl)-2-(trit-yloxy)ethyl methane-sulfonate], a stable inter-mediate, and 5-azido-3-O-benzyl-5-de-oxy-1,2-O-iso-propyl-idene-6-O-tri-phenyl-methyl-β-l-ido-furan-ose, C35H35N3O5 (4) [systematic name: (3aR,5S,6S,6aR)-5-[1-azido-2-(trit-yloxy)eth-yl]-6-benz-yloxy-2,2-di-methyl-tetra-hydro-furo[2,3-d][1,3]dioxole], a substitution product, were examined and the inversion of configuration for the azido group on C-5 in 4 was confirmed. The absolute structures of the mol-ecules in the crystals of both compounds were confirmed by resonant scattering. In the crystal of 3, neighbouring mol-ecules are linked by C-H⋯O hydrogen bonds, forming chains along the b-axis direction. The chains are linked by C-H⋯π inter-actions, forming layers parallel to the ab plane. In the crystal of 4, mol-ecules are also linked by C-H⋯O hydrogen bonds, forming this time helices along the a-axis direction. The helices are linked by a number of C-H⋯π inter-actions, forming a supra-molecular framework.