Desymmetrization of 2,4,5,6-Tetra-O-benzyl-d-myo-inositol for the Synthesis of Mycothiol

Recent Advances in Chemical Synthesis of Amino Sugars

Amino sugars are a kind of carbohydrates with one or more hydroxyl groups replaced by an amino group. They play crucial roles in a broad range of biological activities. Over the past few decades, there have been continuing efforts on the stereoselective glycosylation of amino sugars. However, the introduction of glycoside bearing basic nitrogen is challenging using conventional Lewis acid-promoted pathways owing to competitive coordination of the amine to the Lewis acid promoter. Additionally, diastereomeric mixtures of O-glycoside are often produced if aminoglycoside lack a C2 substituent. This review focuses on the updated overview of the way to stereoselective synthesis of 1,2-cis-aminoglycoside. The scope, mechanism, and the applications in the synthesis of complex glycoconjugates for the representative methodologies were also included.

Synthetic utility of endocyclic cleavage reaction

Existence of endocyclic cleavage reaction is now clearly shown from experimental evidence of endocyclic cleavage reaction as well as computational chemistry. Not only stereoelectronic factor, several factors could be main factors for endocyclic cleavage reaction. Endocyclic cleavage reaction is useful for 1,2-cis aminoglycoside formation, which is difficult by conventional glycosylation. By using endocyclic cleavage reaction, several glycosides with 1,2-cis aminoglycoside were prepared.

Mycothiol synthesis by an anomerization reaction through endocyclic cleavage

Mycothiol is found in Gram-positive bacteria, where it helps in maintaining a reducing intracellular environment and it plays an important role in protecting the cell from toxic chemicals. The inhibition of the mycothiol biosynthesis is considered as a treatment for tuberculosis. Mycothiol contains an α-aminoglycoside, which is difficult to prepare stereoselectively by a conventional glycosylation reaction. In this study, mycothiol was synthesized by an anomerization reaction from an easily prepared β-aminoglycoside through endocyclic cleavage.

Synthesis of the heparin-based anticoagulant drug fondaparinux

Fondaparinux, a synthetic pentasaccharide based on the heparin antithrombin-binding domain, is an approved clinical anticoagulant. Although it is a better and safer alternative to pharmaceutical heparins in many cases, its high cost, which results from the difficult and tedious synthesis, is a deterrent for its widespread use. The chemical synthesis of fondaparinux was achieved in an efficient and concise manner from commercially available D-glucosamine, diacetone α-D-glucose, and penta-O-acetyl-D-glucose. The method involves suitably functionalized building blocks that are readily accessible and employs shared intermediates and a series of one-pot reactions that considerably reduce the synthetic effort and improve the yield.

Total syntheses and structural validation of lincitol A, lincitol B, uvacalol I, uvacalol J, and uvacalol K

First total syntheses of lincitol A, lincitol B, uvacalol I, uvacalol J and uvacalol K were achieved in racemic form, validating their structure from a common intermediate, which was synthesized in six steps from low-cost and extensively available myo-inositol.

Nickel-catalyzed α-glycosylation of C(1)-hydroxyl D-myo-inositol: a formal synthesis of mycothiol

Formal synthesis of mycothiol has been developed via nickel-catalyzed α-glycosylation of the C(1)-hydroxyl group of D-myo-inositols with C(2)-N-substituted benzylideneamino N-phenyl trifluoroacetimidate donors. The pseudo-oligosaccharides were obtained in good yield and with excellent α-selectivity. Removal of the C(2)-N-2-trifluoromethylphenyl-benzylidene group under mild conditions provides a pseudo-disaccharide, completing the formal synthesis of mycothiol.