Isorotation Rule, Hudson

Hudson isorotation rules, III, 17 Hyaluronic acid, II, 164, 179 sulfate, II, 164, 184... 

Baker trans rule or the Hudson isorotation rules have to be taken with care in view of some anomalies.11,38,39 Nuclear magnetic resonance spectra 38 and optical rotatory dispersion curves 38,40,41 have been recently applied to determine the configuration of pyrimidine nucleosides at the anomeric center. 

The negative optical rotation of 5-acetamido-5-deoxy-a-D-xylopyra-nose is in contradiction to its existence as the a-D anomer. As Fig. 2 shows, the methyl D-xylopyranoside that corresponds to the a-D form, according to the Hudson isorotation rule, shows a positive plain curve and the p-D form shows a negative plain curve in optical rotatory dispersion. On the other hand, 5-acylamido-5-deoxy-a-D-xylop)franoses and their glycosides exhibit negative plain curves. Obviously, the... 

Benzyloxycarbonyl)amino]-5-deoxy-D-ribopyranose (208) was separable into its two anomers. In accordance with the above concept, the a-D anomer shows an upward mutarotation and a negative plain curve, whereas the )8-d anomer exhibits a downward mutarotation and a positive plain curve. A further deviation from the Hudson isorotation rule is observable with 4-acetamido-l-0-acetyl-4-deoxy-2,3,5-tri-0-p-nitrobenzoyl-/8-D-ribofuranose. ... 

If the amide chromophore is removed from methyl 5-[(benzyloxy-carbonyl)amino]-5-deoxy-a-D-xylopyranoside (40), or from its non-glycosidic form (31),a positive plain curve of optical rotatory dispersion is found for 5-amino-5-deoxy-D-xylopyranose (17) and its methyl glycoside (41). Because, at least with the glycoside 41, no reversal of configuration at C-1 is to be expected under these conditions, 5-amino-5-deoxy-D-xylopyranose and its methyl glycoside likewise show a tendency to assume the o-D anomeric form, and show plain curves in agreement with the Hudson isorotation rule. ... 

Hudson isorotation rules. For anomeric (a and (3) sugars, Hudson s isorotation rule states that (1) the rotation of carbon 1 in many sugar derivatives is affected in only a minor degree by changes in the structure of the rest of the molecule and (2)... 

The uniqueness of the aldofuranosides, as compared to the aldopyrano-sides, was recognized initially through the difference in rates of hydrolysis by acid. This difference was confirmed by the use of methylation techniques the latter have, to a great extent, been supplanted by the periodate oxidation of Jackson and Hudson120 and by oxidation with lead tetraacetate. Hudson s rules of isorotation were also employed to a great extent. 

Exceptions to Hudson s Rules of Isorotation. The Nuclear Magnetic Resonance Spectra of Anomeric Pyrimidine 2-Deoxy-D-ribonucleo-sides, R. U. Lemieux and M. Holfer, Can. J. Chem., 39 (1961) 110-115. 

Application of Hudson s Isorotation Rules to 2-Amino Sugar Derivatives... 

Later a number of other oligosaccharides of trehalose type were prepared.49 A trehalose, assigned the a, -configuration on the basis of Hudson s rules of isorotation,47 was prepared in 15% yield by treating a toluene solution of D-glucose tetraacetate first with zinc chloride and then with phosphorus pentoxide. 

Hudson s rules of isorotation are used for the determination of the configuration at the anomeric centers in oligo- and poly-saccharides and Korytnyk has discussed some extensions of these rules. Reeves has demonstrated that studies of the optical rotation in cuprammonia solution can give valuable information on the types of linkages and also on the conformation of sugar residues in a polysaccharide. Bourne and coworkers have shown that some o- and /S-D-glycosidic linkages display characteristic absorptions in the infrared at 844 and 891 cm, respectively. 

Hudson observed similarities in the rotatory power of some configurationally related examples he was, however, unable to generate workable isorotation rules for the dithioacetals276,417 later advances in conformational analysis32,33 1 0 2,344 have revealed that the conformational uniformity implicit in the isorotation treatment is not... 

Since both acids may be degraded to Al-acetylneuraminic acid, they evidently differ as regards the position of the 0-acetyl group. The possibility that they are anomers is indicated on comparing their molecular rotations with that of Al-acetylneuraminic acid ([M] — 9,888) and applying Hudson s isorotation rules. 

This study is of interest because Davoll and Lythgoe observed that the more deaiirorotatory anomer of the acylated theophylline nucleosides yielded the more Uvo-rotatory anomer of the free nucleoside. Because of this anomaly, these investigators suggested that the isorotation rules of Hudson have only hmited validity in the case of nucleosides of 2-deoxy-D-ribose and were unable to assign a definite configuration to the anomers. 

Ultraviolet, infrared, and x-ray data on compound 45 have been reported,81 and it has been pointed out4 that, in this series, the anomeric pairs of glycosides that have so far been examined conform with Hudson s isorotation rules, unlike some 2,3-unsaturated glycosyl esters.51,91 Features of the nuclear magnetic resonance spectra are... 

After methylation of compounds (50, R = Me) and (51, R=Me) with methyl sulfate, four isomeric pyranosides were isolated by gas-liquid chromatography by detailed nuclear magnetic resonance studies, these were shown to exist in the H° conformation.103 Unlike related esters (see p. 221), but like other 2,3-unsaturated glycosides (see p. 237), these anomeric pairs of glycosides were found to conform with Hudson s isorotation rules. In dilute acid, they are degraded to methyl 3,4-dideoxy-6-0-methyl-a- and /3-D-g/ycero-hex-3-enopyrano-sidulose (52) these also were characterized configurationally and conformationally by nuclear magnetic resonance methods. 

Hudson s isorotation rule was subsequently expanded by Whiffen, who suggested a set of empirical rules based on additive contributions to the molecular rotation based on contributions along each asymmetrically substituted bond. He established six structural parameters and assigned to each of these a numerical value, making possible an estimation of the molecular rotation in aqueous solution of the various pyranoses.195... 

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