Bicyclic carbohydrate structures

Basset s catalyst was also used for the intramolecular metathesis of diluted solutions of di- and tri-substituted w-unsaturated glucose and glucosamine derivatives, affording bicyclic carbohydrate-based structures in reasonable yields (Equations (119)—(122)).141... 

Nucleosides with conformationally restricted carbohydrate rings (locked nucleic acids—LNA) are RNA mimics containing the 2 -0,4 -C-methylene linkage. The bicyclic structure locks... 

In the light of the analogy between the structures of these alkaloids and glucose, some of the above mentioned enzymatic methods for the selective functionalization of carbohydrates were applied to prepare several acyl derivatives of 155 and 160. Thus, subtilisin transfers the acyl moieties from several activated esters to the 1-OH group of the bicyclic base in moderate to high yields (Fig. 18-22)[265, 2661. Again,... 

Several carbohydrate-based bicyclic and tricyclic phosphoramidates and phosphoramidothioates have been prepared in selected pure diastereoisomeric forms characterized structurally by X-ray techniques. Such compounds include (99) derived from... 

Applications of the aldol method are not restricted to carbohydrates or carbohydrate-derived materials, despite obvious advantages. This was impressively illustrated, e.g., by FruA-based chemoenzymatic syntheses of the insect pheromone (+)-ejc< -brevicomin (76 Fig. 26) [141,142]. Due to the fact that the (/ ,i )-configurated threo-diol substitution pattern, which is masked in the bicyclic structure of 76 as an intramolecular acetal but comprises the only independent stereogenic centers of brevicomin, is symmetrical to chain... 

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