Alpha and beta methyl lyxosides, mannosides, gulosides, and heptosides of like configuration

Abstract

Eleven new su~ar der ivatives and numerous optical rotation and hydrolysis measurements are r eported. A comparison of the alpha and beta methyl glucosides, mannosides, galactosides, and gulosides shows that the configurations of all of the asymmetric carbons in the pyranose ring affect the rate of hydrolysis, and that there is no fixed relationship between the configuration of the glycosidic carbon and the relative rates for the hydrolysis of the alpha and beta modifications. The configur ation of carbon 3 appears to influence markedly the relative rates for the hydrolysis of the alpha and beta modifications. Aldo-pyranosides having trans configurations for carbons 1 and 3 are hydrolyzed more slowly than the corr esponding modifications having cis configurations for carbons 1 and 3. This unexpect edly large influence of carbon 3, and the close resemblance of each pent ose t o the corresponding h exose which has t he trans configuration for carbons 3 and 5 are discussed in r elation to t he spacial arrangement of the whole molecule. The similarity of the methyl gulosides and a-glucoheptosides on the one hand, and t he methyl Iyxosides, mannosides, and a-galaheptosides on the other hand, furnishes a substantial basis for the allocation of Iyxose to the mannose series. CONTENTS

THE RELATIVE REACTIVITIES OF 1,2-trans-SUGAR ACETATES

“…The deactivation which results on the introduction of a CHzOAc group for a hydrogen atom a t C5 of a pentose acetate is reminiscent of the same result found in the hydrolysis of methyl glycopyranosides (12). The present discovery that the configuration of C5 in the case of the hexose acetates has only a twofold to threefold effect on reactivity was unexpected in view of the important role the CH20Ac group has been predicted to play in determining the reactivity of related compounds (9).…”

Ring structures and mutarotations of the modifications of D-galacturonic acid

“…In publications from this laboratory it has been emphasized that substances having like configurations for the atoms comprising the pyranose ring have similar properties [2,3,5]. It therefore seemed of interest to compare the mutarotation curves of the modifications of galacturonic acid with those of a-and ,B-D-galactopyranose.…”

Carbohydrate-Specific Antibodies in Normal Human Sera

“…Mono-and disaccharides were obtained from com mercial sources, except for methyl-ß-mannoside which was synthesized according to the method of Isbell and Frush [1940], Sera, obtained from normal donors and stored at -20 °C, were tested as described in the previous paper. In brief, human erythrocytes were incubated with various sugars washed, and then used as indicator cells in the passive hemagglutination reaction per formed both manually and in an AutoAnalyzer contin uous flow system.…”