Biomedical subjects
Publications and source records attributed to Fabien P Boulineau.
The high facioselectivity in the epoxidation of 4-deoxypentenosides (4-DPs) by dimethyldioxirane (DMDO) correlates with a stereoelectronic bias in the 4-DPs' ground-state conformations, as elucidated by polarized-pi frontier molecular orbital (PPFMO) analysis.
Methyl D-glucoside and d-glucose pentaacetate are transformed, respectively, into methyl alpha-O-glucuronide 3 and hydroxymethyl beta-C-glucuronide 9, which undergo decarboxylative elimination efficiently to produce 4-deoxypentenoside 4 and L-glucal 10. These unsaturated pyranosides provide an expeditious entry into mirror-image oligosaccharides, as demonstrated in the synthesis of the unnatural enantiomer of the H-type II blood group determinant trisaccharide (D-Fuc-(alpha1-->2)-L-Gal-(beta1-->4)-L-GlcNAc-beta-OMe). This work illustrates that D-glucose, a common starting material in the synthesis of naturally occurring carbohydrates, can also be used to prepare their mirror-image analogues.
[reaction: see text] L-Glycals can be prepared in seven steps from readily available D-glucals, enabling the facile construction of mirror-image carbohydrates such as the L-lactosamine derivative shown above.
Frozen-solution conformational analysis (FrSCA) can be performed on organic compounds using REDOR spectroscopy. REDOR measurements on frozen aqueous solutions of 13C-methyl beta-15N-aminoglucoside indicate a bimodal distribution of conformations in a 68:32 ratio, with 13C-15N distances of 4.31 and 3.55 A, respectively. The high resolution and straightforward sample preparation make FrSCA an attractive alternative to solution-based NMR methods of conformational analysis.
[reaction: see text] 4-Deoxypentenosides, which are readily derived from D-sugars, resemble glycals in structure and reactivity and can undergo stereoselective epoxidation and S(N)2 nucleophilic addition to produce L-sugars in pyranosidic form.