Glycosides 2,3-unsaturated

Methyl glycosides of 2 deoxy sugars have been prepared by the acid catalyzed addition of methanol to unsaturated sugars known as glycals... 

F E R R I E R Chiral cyclohexanone synthesis Transtormatlon o< unsaturated glycosides into cyclohexanone derivatives by heating in aqueous acetone with mercury (II) salts... 

The widespread occurrence and biological significance of polyoxygenated carbocycles provided the impetus to apply RCM to sugar-derived dienes. Carbohydrate carbocyclization based on a sequence of Vasella reductive opening of iodo-substituted methyl glycosides [25], and RCM of the dienes available from the resulting unsaturated aldehydes, were used to prepare a series of natural compounds (Schemes 5-7). 

The classic seed burial studies of W. J. Beal and his successors have shown seeds of at least one weed species, Moth Mullein (Verbascum blattaria L.) can remain viable in soil for a peiod of 100 years, whereas three species continued to germinate after 80 years of burial (30). Weed seeds not only resist decay by soil microbes, but they vary in dormancy characteristics. There is considerable evidence that chemical inhibitors are responsible for both phenomena. Unsaturated lactones and phenolic compounds in particular, are potent antimicrobial compounds present in many seeds (4J. Fruits and seeds are also known to contain diverse germination inhibitors including phenolic compounds, flavonoids and/or their glycosides and tannins. Unique methods to destroy inhibitors could provide an excellent weed management strategy. 

The presence of the C15 saturated chain displayed an efficient gelling ability in a wide range of organic solvents, water, and protic solvent mixtures (1 1), whereas the unsaturated derivatives (mixture of four molecules) formed fibrous nanostructures as opposed to stronger gels. The diene and triene components of the cardanyl glycosides in their fully hydrated state formed fluid nanostructures at room temperature and could not self-assemble to form gels. 

P. Tiwari, G. Agnihotriand, and A. K. Misra, Synthesis of 2, 3-unsaturated C-glycosides by HC104-Si02 catalyzed Ferrier rearrangement of glycals, Carbohydr. Res., 340 (2005) 749-752. 

The Tsuji-Trost reaction is the palladium-catalyzed allylation of nucleophiles [110-113]. In an application to the formation of an A-glycosidic bond, the reaction of 2,3-unsaturated hexopyranoside 97 and imidazole afforded A-glycopyranoside 99 regiospecifically at the anomeric center with retention of configuration [114], Therefore, the oxidative addition of allylic substrate 97 to Pd(0) forms the rc-allyl complex 98 with inversion of configuration, then nucleophilic attack by imidazole proceeds with a second inversion of configuration to give 99. 

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