Highly Selective Indium Mediated Allylation of Unprotected Pentosylamines

Protecting-group free synthesis of glycoconjugates displaying dual fungicidal and plant defense-eliciting activities

A straightforward synthesis of carbohydrate templated isoxazolidines is described, by reaction of unprotected glycosylhydroxylamines (operating as 1,3-dipoles) with methyl acrylate using microwave activation. Rhamno- and erythro-isoxazolidines are recognized by plant cells, resulting in a strong ROS-production as a plant immune response, and exert a high antifungal activity against Botrytis cinerea.

Dichotomous Selectivity in Indium-Mediated Aza-Barbier-Type Allylation of 2-N-Acetyl Glycosyl Sulfinylimines in Brine: Convenient Access to Potent Anti-Influenza Agents

A highly diastereoselective indium-mediated allylation of 2-N-acetyl glycosyl sulfinylimines in brine under mild reaction conditions is reported. The method allows the achievement of a highly remarkable dichotomous selectivity for substrates, providing a single diastereoisomer of the product in 80-98% yield. With chiral (S)-homoallylic sulfinamide (R_S)-5 and (R_S)-8 formed as key intermediates, two potent anti-influenza agents, zanamivir and zanaphosphor, were synthesized in 50% and 41% overall yields, respectively.

Broadening the reaction scope of unprotected aldoses via their corresponding nitrones: 1,3-dipolar cycloadditions with alkenes

Condensation reactions of unprotected tetroses and pentoses with hydroxylamines afforded nitrones, which were easily converted to densely functionalized isoxazolidines in the presence of electron-poor alkenes. The 1,3-dipolar cycloaddition occurred with good facial discrimination of the chiral nitrone but under rather low endo/exo control. Stereochemistry of isomers was ascertained by chemical correlation with known derivatives from the literature. Microwave activation appeared as the most efficient reaction mode, affording the expected adducts within several minutes whereas hours were needed under standard heating. Alternatively, the transformation proved also possible under high pressure conditions by using a hand pump system, avoiding any energy source. Although water could not be used as the solvent, leading to hydrolysis of the nitrone substrate, a large variety of organic solvents proved efficient. The method has potential use in the preparation of non-ionic carbohydrate-based amphiphiles.

Glycoside Mimics from Glycosylamines: Recent Progress

Glycosylamines are valuable sugar derivatives that have attracted much attention as synthetic intermediates en route to iminosugar-C-glycosyl compounds. Iminosugars are among the most important glycomimetics reported to date due to their powerful activities as inhibitors of a wide variety of glycosidases and glycosyltransferases, as well as for their use as pharmacological chaperones. As they provide ready access to these important glycoside mimics, we have reviewed the most significant glycosylamine-based methodologies developed to date, with a special emphasis on the literature reported after 2006. The groups of substrates covered include N-alkyl- and N-benzyl-glycosylamines, N-glycosylhydroxylamines, N-(alkoxycarbonyl)-, and N-tert-butanesulfinyl-glycosylamines.

Direct synthesis of C-glycosides from unprotected 2-N-acyl-aldohexoses via aldol condensation–oxa-Michael reactions with unactivated ketones

C-glycosides were synthesized from unprotected 2-N-acyl-aldohexoses and unactivated ketones in one pot via aldol condensation–oxa-Michael reactions.

β-Xylopyranosides: synthesis and applications

In recent years, β-xylopyranosides have attracted interest due to the development of biomass-derived molecules. This review focuses on general routes for the preparation of β-xylopyranosides by chemical and enzymatic pathways and their main uses.

Efficient synthesis of glycosylamines in solventless conditions promoted by mechanical milling

A mecanosynthesis of glycosylamines under solventless conditions was established. This environmentally friendly approach optimized with l-rhamnose, was investigated using a variety of amines and other carbohydrates.

Iminosugar-ferrocene conjugates as potential anticancer agents

We prepared a series of new iminosugar-ferrocene hybrids displaying potent inhibition of fucosidase (bovine kidney) and inactivation of MDA-MB-231 breast cancer cells proliferation at low micromolar concentrations. The synthetic route brought to light an unprecedented isomerisation of a 2-ethanalylpyrrolidine.