Glucose-1,2,3,4-tetraacetate, preparation

A critical study of the preparation of the two anomeric 6-desoxy-D-glucose tetraacetates (LXXXIV) from D-glucose has been made by Hardegger and Montavon.70 The final step, namely, the reduction of the two 6-iodo-6-desoxy-D-glucose tetraacetates (LXXXII) in high yield, proved to be particularly difficult and a variety of methods were studied. Highest yields were obtained when LXXXII was allowed to react with thiourea to form the S-substituted isothiuronium iodide (LXXXIII) which was then desulfurized with Raney nickel. In actual practice the 6-iodo derivative was refluxed briefly in amyl alcohol with thiourea and... 

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. 

Thioglucobioses (69a) and (70a) were easily prepared from 2-0-triflyl-man-nose tetraacetate (68) and 1-thio-glucoses (8a) or (10b). However, Zemplen 0-deacetylation led to an intractable mixture of compounds. Thus, prior to methoxide treatment, the readily cleavable allyl group was introduced at the anomeric position (Scheme 22) [20] of the acetylated disaccharides (69a) and (70a). Benzyl -thiokojibioside (70c) was also prepared by condensation of (68) and (16a) [29bj. 

Niemann and Hays later showed that the oxidation of one mole of iV-acetyl-D-glucosylamine by lead tetraacetate involves the slow consumption of slightly more than two moles of oxidant, so confirming the result of periodate oxidation. Hockett and Chandler prepared an isomeric N-acetyl-D-glucosylamine, also cyclic since it gives a tetraacetate, by the action of 29 % aqueous ammonia on aldehydo-D-glucose pentaacetate or on hexa-0-acetyl- a -D-glucoheptonic nitrile. The oxidation of this isomer produced formaldehyde (isolated as its 2,4-dinitrophenylhydrazone), but... 

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