Publisher Summary This chapter discusses the important reactions of the hydroxyl group. Knowledge of the relative reactivities of hydroxyl groups in carbohydrates is fundamental to a thorough understanding of carbohydrate chemistry. The chapter explains esterification, which forms the largest part of the literature since 1953 on selective reactions of carbohydrates. The common methods of esterification utilize an acid chloride or an acid anhydride as the reagent, but other acid derivatives often show different selectivities. An investigation pertinent to the subject of favored reactivity concerned the reactions of certain acyl halides with ethanol, in acetone or chloroform solution. The mixed-order nature of some of these reactions suggested that every rate-determining transition-state contained the substrate, the nucleophile (ethanol), and an acceptor— X—for hydrogen bonding, suitable acceptors being an acetone molecule, a chloride ion, or another ethanol molecule. The possibility that intramolecular hydrogen-bonding does not persist in pyridine and that the advantage of a bonded hydroxyl group would be lost, invalidates the explanation of favored reactivity. But if the hydrogen-bonding to pyridine is hindered in the transition state, intramolecular hydrogen-bonding could conceivably assume importance.

Relative Reactivities of Hydroxyl Groups in Carbohydrates

Candida lipolytica synthetisiert das Antibioticum Tryptanthrin aus 1 Mol Tryptophan und 1 Mol Anthranilsaure. Bei Verfutterung von Tryptophan und substituierter Anthranilsaure, bzw. substituiertem Tryptophan und Anthranilsaure, konnten die zu erwartenden Tryptanthrinderivate isoliert und identifiziert werden. Die Enzyme der Tryptanthrinbiosynthese wiesen in bezug auf diese Substrate, mit Ausnahme von Bromtryptophan, keine Spezifitat auf. Parallel zu diesen Versuchen wurden durch chemische Synthese substituierte Tryptanthrine hergestellt. Die Dierivate wurden auf ihre antibiotische Wirksamkeit gepruft; als besonders wirksam erwiesen sich die halogenierten Verbindungen.

Stoffwechselprodukte von Mikroorganismen

Publisher Summary This chapter focuses on oxirane derivatives of aldoses. The chapter discusses methods available for their synthesis, with special reference to their ease of formation, together with their reactions and the methods available for their characterization. Carbohydrate oxiranes are commonly called as “epoxides.” It is noted that their nomenclature system is based on the anhydride principle, the oxirane being considered as derived from the aldose of corresponding configuration by removal of the elements of water. Aldose oxiranes are essentially used as intermediates in the synthesis of a variety of modified sugars—including deoxy, amino, thio, and branched-chain sugars, and the rarer simple sugars. The standard method for the formation of the oxirane ring in carbohydrate compounds is the treatment with alkali of sulfonic esters having vicinal, trans-hydroxyl groups that are free or esterified.

Oxirane Derivatives of Aldoses

On the communication of chirality from furanose and pyranose rings to monosaccharide side chains: anomalous results in the glucose series

Publisher Summary This chapter discusses the sugars of the cardiac glycosides, which are a group of plant materials arbitrarily named because of their specific digitalis-like effect on the heart muscle. Their physiological activity is primarily dependent on the nature of the aglycon rather than on the carbohydrate component. These drugs usually consist of mixtures that are found in quite dissimilar plants, the Apocynaceae and Asclepiadaceae being especially rich in them. Chemically, the cardiac glycosides are steroid derivatives that fall into two types depending upon the aglycon. The cardiac glycosides thus defined do not all exhibit digitalis-like properties. The corresponding glycosides occur in the same plants but have not been isolated in pure form. These substances are classified with the digitaloid lactones because of analogous structures, even when they exhibit no digitalis-like activity.

The Sugars of the Cardiac Glycosides

Die Lithiumaluminiumhydrid-Reduktion von 4, 6-Ditosyl-2, 3-anhydro-α-methyl-D-allosid liefert je nach der gewahlten Reaktionsdauer entweder α-Methyl-D-digitoxosid oder sein 4-Tosyl-Derivat, das leicht in Cymarose ubergefuhrt werden kann. Die beschriebenen Reaktionen stellen die gleichzeitige Reduktion einer Hexose in der 2-und in der 6-Stellung dar.

Neue Synthesen für Digitoxose und Cymarose. Desoxyzucker, 27. Mitteilung

3‐Desoxy‐d‐mannose. Desoxyzucker. 11. Mitteilung

2‐Tosyl‐4, 6‐benzyliden‐α‐methyl‐d‐glucosid‐〈1,5〉 und 4,6‐Benzyliden‐α‐methyl‐d‐glucosid‐〈1,5〉‐3‐methyläther

Die Synthese der D-Xylo-2-desoxy-hexamethylose auf verschiedenen Wegen wird beschrieben. Der Zucker erwies sich als identisch mit naturlicher Boivinose, die in Zukunft somit als D-Boivinose bezeichnet werden kann.

Synthese der D‐Xylo‐2‐desoxy‐hexamethylose (III) und ihre Identifizierung mit Boivinose. Desoxyzucker, 29. Mitteilung

Bei der Reduktion von 4,6-Ditosyl-2,3-anhydro-α-methyl-D-allosid mit Lithiumaluminiumhydrid reagieren die 3 funktionellen Gruppen in der Reihenfolge Anhydroring > prim. Tosylgruppe > sek. Tosylgruppe. Je nach den gewahlten Bedingungen lassen sich so Derivate der 2-Desoxy-D-allose, der Digitoxose oder der Cymarose bereiten.

H. R. Bolliger

Papers

Neue Synthesen für Digitoxose und Cymarose. Desoxyzucker, 27. Mitteilung

3‐Desoxy‐d‐mannose. Desoxyzucker. 11. Mitteilung

2‐Tosyl‐4, 6‐benzyliden‐α‐methyl‐d‐glucosid‐〈1,5〉 und 4,6‐Benzyliden‐α‐methyl‐d‐glucosid‐〈1,5〉‐3‐methyläther

Synthese der D‐Xylo‐2‐desoxy‐hexamethylose (III) und ihre Identifizierung mit Boivinose. Desoxyzucker, 29. Mitteilung

4,6-Ditosyl-2-desoxy-α-methyl-D-allosid. Desoxy-zucker, 28. Mitteilung