Anhydro Hexoses

An alternative route to a furanosyl halide of 2-deoxy-D-nbo-hexose was envisaged, involving the lithium aluminum hydride reduction of ethyl 2,3-anhydro-/ -D-allofuranoside which could, presumably, lead to ethyl... 

Deoxy-D-jcylo hexose 6-(dihydrogen phosphate) (21) has also been synthesized (2) the reaction sequence makes use of 3-deoxy l 2,5 6-di-O-isopropylidene D-galactofuranose (16), a compound that can be easily prepared from D-glucose (2, 60). The mono-isopropylidene derivative (17) formed by partial hydrolysis of the di-ketal is converted into the 6-tosylate (18) by reaction with one molar equivalent of p-toluenesulfonyl chloride. From this the epoxide (19) is formed by reaction with sodium methoxide. Treatment of the anhydro sugar with an aqueous solution of disodium hydrogen phosphate (26) leads to the 6-phosphate (20)... 

Sarmentose Sedoheptulose Sedoheptulosan Solatriose 2.6- Dideoxy-3-0-methyl-D-xy/o-hexose D-a/froHept-2-ulose 2.7- Anhydro P-D-a/fro-hept-2-ulopyranose a-L-Rhamnopyranosyl-(1 ->2)-[P-D-glucopyranosyl-(1->3)]-D-galactose... 

V. Anhydro Sugars op the Hydropuranol Type 1. 3,6-Anhydro Hexoses... 

This procedure provided the most important method for the synthesis of anhydro sugars of the hydrofuranol type. 3,6-Anhydro sugars have resulted from the saponification of hexoses esterified at C6 by the following cationogens Br- 3 36 14- 36 CH3 C H4 S020 37, 3S- 39> 40 HO-SCVO-41 42 02N-0-.43 It is very probable that the phosphate ion is also cationogenic and that saponification of a hexose 6-phosphate... 

Our present knowledge of the second type of hydrofuranol anhydro sugars, the 2,5-anhydro hexoses, is less extensive and definite than is the case with the 3,6-anhydro type. The credit for most of the information we have belongs to Levene and coworkers and results from the comprehensive study of hexosamines made by them. A good summary of this work was provided by Levene in 1921.49... 

The best known 2,5-anhydro hexose is that which was prepared in 1894 by Fischer and Tiemann4 and named by them chitose. Chitose is a liquid with ill-defined properties and is usually characterized by its oxidation derivatives, chitonic acid and isosaccharic acid. It is prepared by the deamination of the naturally occurring chitosamine (D-glu-cosamine). 

The failure of a compound to undergo periodate oxidation can not be regarded as positive proof that it contains no 1,2-glycol structures. If the glycol is securely locked in a trans position, oxidation has been shown not to occur. This resistance has been encountered in the bicyclic anhydro hexoses, for example, l,6-anhydro-/3-D-glucofuranoseM and 1,6-anhydro-a-D-galactofuranose.54 This work has already been summarized in this... 

Abbau von vier 3,6-Anhydro-hexose-phenylosotriazolen zu kristallisierten antipo-den Dialdehyd-hydraten, by E. Schreier, G. Stohr, and E. Hardegger, Helv. Chim. Acta, 37 (1954) 574-583. 

Tables V-LVII detail H and F shift and coupling information, and Tables LVIII to LXXI incorporate the C-n.m.r. data. The data within this compilation are arranged according to the following outline hexoses prior to pentoses, followed by anhydro sugars, sugar acids and lactones, amino sugars (and their synthetic, A -containing precursors), mono-, di-, and tri-deoxy sugars, branched derivatives, ketoses, polyfluorinated monosaccharides, and, finally, difluorinated amino sugars. Within this compilation, and even within each table, pyranoid derivatives are listed prior to their furanoid counterparts, hexoses prior to pentoses, functionalized prior to deoxy compounds the arrangement within each sub-table is made alphabetically.

Aus Triose-, Tetrose- und Pentose-osazonen entstehen in alkoholischer Losung 3-Alkoxy-osazone (vgl. S. 457), wahrend Hexose-osazone intra-molekular an intermediar gebildete Phenylhydrazono-en-phenyl-azo-Systeme zu 3.6-Anhydro-osazonen addieren ) (vgl. S. 458). 

Bildung von (bis jetzt nicht gefafiten) En-azo-phenylhydrazonen 106 - -118), die im Falle von Pentosen, Tetrosen und evtl. auch Triosen Alkohol zu 3-0-Alkyl-phenylosazonen addieren 118 - - 7/Pbzw. 120) und im Falle von Hexose-osazon eine intramolekulare Addition zu Anhydro-osazonen 121, 122) erfahren. 

A. C. Richardson and H. O. L. Fischer, Cyclizations of dialdehydes with nitromethane, Part V. Preparation of some 3-amino-l,6-anhydro-3-deoxy-P-D-hexoses and the elucidation of their structures, Proc. Chem. Soc. (1960) 341-342. 

---