2.5- anhydro-D-, preparation

Sugihara and Schmidt49 reported the isolation of 2,5-anhydro-D-glucitol in crystalline form its preparation on a relatively large scale has been described in the patent literature,50 and consists in the thermal dehydration of D-mannitol. The process leads to the formation of 1,4-anhydro-D-mannitol, 1,5-anhydro-D-mannitol, 1,4 3,6-dianhydro-D-mannitol, and 2,5-anhydro-D-glucitol, which is isolated as the crystalline 1,3-O-isopropyIidene derivative (35). 

Starting with the same acetal (35), but proceeding by way of the diacetate 40, instead of the dibenzoate 36, it was possible to prepare,51 in high yield, the p-toluenesulfonate 41 by sequential trityla-tion and p-toluenesulfonylation. Compound 41 was then subjected to solvolysis in the presence of sodium acetate in moist N,N-dimethyl-formamide, and the product (42) was successively acetylated and de-tritylated to give 3,4,6-tri-0-acetyl-2,5-anhydro-D-allitol (43). The... 

The action of 1% methanolic hydrogen chloride on 1,2-O-iso-propylidene -3,5-di - O - p-tolylsulfonyl-D-xylofuranose (65) leads,81 after boiling for three hours under reflux, to 2,5-anhydro-3-0-p-tolylsulfonyl-D-xylose dimethyl acetal (66). The structure of 66 was demonstrated by conversion into the disulfonate 67 this was prepared independently from a 2,5-anhydro-D-xylose dialkyl dithio-acetal72 (48) by p-toluenesulfonylation followed by exchange of the acetal group in methanol in the presence of mercury salts. 

Starting from the appropriate sulfonylated acetals 105, 106, and 107 (from 2,5-anhydro-D-ribose, -D-xylose, and -D-lyxose, respectively), the application of a method for elimination of vicinal, secondary disulfonates by reaction with sodium iodide in lV,IV-dimethylformamide in the presence of zinc112 has permitted"3 the preparation of the... 

Grant74 conducted a detailed study of the properties of 2,5-anhydro-D-mannose (chitose), and prepared several new derivatives that confirmed the anhydrohexose structure. The mutarotation of 2,5-anhydro-D-mannose, its conversion under mild conditions into a... 

J. Defaye, Desamination nitreuse de la D-galactosamine. Preparation des 2,5-anhydro-D-taIose et 2,5-anhydro-D-taIitoI, Bull. Soc. Chim. Fr. p. 999 (1964). 

A double-headed example, 2,5-anhydro-l,6-bis(4-amino-5-aminocar-bonyltriazol-3-yl)-l,6-dideoxy-3,4-di-0-methyl-D-glucitol (55), was similarly prepared from 1,6-diazido-1,6-dideoxy-3,4-di-0-methyl-2,5-anhydro-D-glucitol (25°C, 15 hr, 49%). [Note glucitol (sorbitol) is a hexitol] (83 ACH443). 

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