Pyranose Systems

All isomers of tetra-O-acetyl-D-glucopyranose and the corresponding monobenzyl and monotrityl ethers have synthesized and their 

H- and C-n.m.r. spectra completely assigned. The exo-anomerlc effect in the glucosyl diene (3), which determines its di- 

A flexible twist-boat conformation has been assigned to methyl 

The cross polarization-magic angle spinning technique used for C n.m.r. of solid methyl and -D-xylo yranosides has been shown to be sensitive to the crystal packings. 

The substitution pattern in the aromatic nucleus of 2-methoxy-4-hydroxy-phenyl /J-D-glucopyranoside (8), isolated from the liverwort Isotachis. 1 aponica. has been determined with the assistance of an n.O.e. between the anomeric proton and the ortho proton on the aromatic nucleus. C n.m.r. data for N-(m- and -substituted- 

J values. A substituent such as hydroxy, acetoxy, alkoxy, and 

A large amount of chemical shift data obtained in deuterium 

study of ethylidene acetals of model diols and various carbohydrates has shown a relationship of a number of n.m.r. parameters to the ring size of the acetal. The most useful diagnostic 

DMSO-d have been reported, and the stereochemical dependence of 

D-fructose. The spin-lattice relaxation rates of the ring 

D-gluco- and -manno-pyranose have been shown to adopt the 

5) has been achieved by correlations with the spectra of the parent diols. The regio- and stereo- 

The C-n.m.r. spectral characteristics, including T and n.O.e. values, for methyl 3 4-0-(l-carboxyethylidene)- fi-D-fuco- and -galacto-pyranosides have been recorded and compared with those of 4.,6-0-(1-carboxyethylidene)-analogues. The acetal carbon resonance in the pyruvate acetal moiety is at 107 - 109 5 p.p.m. for 5-membered acetals, and 100.5 - 102.4 p.p.m. for 6-membered acetals. The chemical shifts of C-3 and of the pyruvate methyl protons are sensitive to the configuration of the 3 4-(l- 

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As part of an investigation into developing routes to natural sesquiterpinoid ring systems, the application of the Pausen-Khand reaction has led to some unexpected results. Thus the fused [3.3.0]bicyclooctenone-pyranose system 45 was produced as expected when the 3-C-methylene derivative 46 was treated with Co(CO)g in an atmosphere of carbon monoxide. However, the fused [4.1.0]bicy-cloheptene-pyranose system 47 was produced from the 4-C-methylene derivative 48 under similar conditions. ... 

N.M.R. Spectroscopy and Conformational Features Theoretical and General Considerations Acyclic Systems Furanose Systems Pyranose Systems Oligosaccharides Nucleosides Other Molecules... 

In a study of the relative rates of hydrolysis of conformationally restrained a- and jS-4-pentenyl glucosides under neutral conditions, it was concluded that the Deslongchamps theory for glycoside hydrolysis (the anti-periplanar lone pair hypothesis) was not consistent with the results obtained. In work on variously substituted 4-pentenyl glycosides compound (55, either anomer) gave the amide (56) on treatment with N-bromosuccinimide in aqueous acetonitrile, whereas the benzylated analogue (57) underwent hydrolysis in these conditions (Scheme 20). The first result was attributed to the strain imposed by the ring fusions on the pyranose system. 

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