Sugars furanoid

In ortho-annelated, bicyclic, furanoid sugar derivatives, because of lessened conformational flexibility, only a limited number of conformations is thermodynamically favored. The preponderance of the 3T2 conformation found for (furanoid) 1,2-O-isopropylidene-a-D-gluco-and -/8-L-ido-furanoses,76,80 1,2-O-benzyIidene-a-D-glucofura-nose,81 and l,2-0-isopropyIidene-5-0-p-tolylsuIfonyl-a-n-glucofura-nurono-6,3-lactone76 (52) confirms this. 

Amongst the multitude of three-dimensional structures of gramicidin S in the literature [4,32], one asymmetric furanoid sugar-containing analogue indeed forms hexamers with similar intermolecular contacts in the crystal as were derived here in a quasi-native membrane environment [44]. Most... 

For the preliminary communications (Section IV,2), the conformation of the furanoid sugar is denoted by the atom most displaced... 

Carbocyclic analogues of furanoid sugars have represented a relevant topic in the realm of carbasugars ever since the discovery of their occurrence as substructures in natural bioactive compounds, such as carbocyclic nucleosides and certain carbocyclic sugar conjugates [2], at... 

Many unanswered questions remain with respect to the lentil lectins. These include the chemical relationship between the two lectins, a comparison of their carbohydrate-binding specificity, a study of the binding of furanoid sugars (for example, a- and /3-arabinofuranosides) to the lectins, and a determination of the H or O atoms of each hydroxyl group which may be involved in the binding phenomenon. There is also the question as to the size of the binding site will the lentil-lectin site be more complementary to sequences of a-D-(l— 2)-mannopyranosyl residues than is con A (compare Ref. 204) ... 

The molecule of a furanoid sugar, having a five-membered (heterocyclic) ring, has a fairly rigid structure, with all the atoms in the ring lying very nearly in one plane. 

Lithium aluminum hydride reduction of w-sulfonyloxy groups of furanoid sugar derivatives has been used extensively for the preparation of the corresponding w-deoxy sugar derivatives similar results have been obtained with ether or tetrahydrofuran as the solvent Hydride reduction in ether of 3,5-0-benzylidene-l,2-0-isopropylidene-6-0-p-tolylsulfonyl-a-D-glucofuranose and of 3-0-benzyl-l,2-0-isopropylidene-6-0-p-tolylsulfonyl-o -D-glucofuranose afforded the corresponding 6-deoxy derivative similarly, 1,2-O-isopropylidene-... 

Using a C-glycosidic furanoid sugar amino acid, McDevitt and Lansbury [11] prepared a saccharide-peptide hybrid with a three-atom linker, the dimer 26. The homodimer of this C-glycosidic sugar amino acid gave rise to a five-atom spacer as in compound 27 (O Scheme 7) these derivatives have not been reported in deprotected form. 

Those caramels which are prepared from plain sugars without any catalyst present the relatively simplest chemical features. In order the better to understand the complexity of caramelization specific interconversions of sugars in solution have to be kept in mind. It is well known that pyranoid and furanoid sugars are considerably more stable than the acyclic forms. Mu-tarotation of sugars is autocatalyzed by protons, " and, with D-glucose, the equilibrium slightly favors )5-D-glucopyranose over the a anomer. It has... 

The only example thus far reported of an ethyleneimine ring fused to a furanoid sugar derivative was formed similarly. When the 3-amino-3-deoxy-D-arabinofuranoside (245) was treated with aqueous base at room... 

Conformational factors in furanoid sugars can dictate the stability of a frans-benzylthio-sulfonate system toward formation of episulfonium ion. Christensen and Goodman noted that the 3-)S-benzyl-3-thio-D-arabinoside ester (311) requires vigorous conditions for conversion into the mixture of azides (313) that arises by opening of the intermediate ion... 

Furanoid sugar residue Derivative studied Bond length A.) At carbon in ring At Or References... 

In order to increase our understanding of the stereochemistry of cyclic acetals of pyranoid and furanoid sugars, great importance should be attached, in futme studies, to gaining full knowledge of the structure of all of the products resulting from a given condensation. 

Furanoid Sugar Derivatives Having Fused Rings.120... 

V. CONFORMATIONS OF FURANOID SUGARS AND THEIH DERIVATIVES 1. General Considerations... 

The preparation of several furanoid sugar derivatives having a fused oxetane ring has been reported, as, for example, 3,5-anhydro-... 

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