Isopropylidene-ot-D-glucofuranose

A convenient approach for the preparation of 3-deoxy-D-xy/o-hexopyranose (27) starts from 1,2 5,6-di-(9-isopropylidene-ot-D-glucofuranose and proceeds via the 3,4-unsaturated derivative 28 (Scheme 15).80... 

Hydrolytic removal of acetals can be selective, as in the well-known production of 1,2-isopropylidene ot-D-glucofuranose from mild acid-catalysed hydrolysis of l,2 5,6-diisopropylidene ot-D-glucofuranose. °° The difference in reactivity of the two isopropylidene derivatives lies in the differing stabilities of the oxocarbenium ion intermediates. Under acid-catalysed conditions, a cyclic ketal with different electron demand at the alcohol sites will first open to give the most stable oxocarbenium ion leaving group ability is not an issue... 

Attempts were made to prepare a terminal 5,6-epiminofuranose derivative by treatment of 6-benzamido-6-deoxy-l,2-(9-isopropylidene-5-(9-methanesulfonyl-ot-D-glucofuranose with lithium aluminum hydride or sodium ethoxide. In both cases, only 6-benzamido-6-deoxy-l,2-(9-isopropylidene-ot-D-glucofuranose was obtained, indicating hydrolysis of the methanesulfonate. b. A-Aryl(alkyl)sulfonylamines.—In comparison with the preceeding method, eyelization of vicinal sulfonamido-sulfonates has two advantages formation of oxazolines is excluded, and the reaction proceeds more readily because of enhanced acidity of the N-H group and facile formation of the N anion, which is considered the reactive species. Lower temperatures and weaker bases are therefore sufficient to induce eyelization. 

The detection of stable periodate complexes having a tridentate structure also supports the concept of the cyclic intermediate. These complexes are formed at neutral and high pH by ot-o-ribopyranose and other dx,cw-l,2,3-triols, and by such compounds as l,2-(9-isopropylidene-ot-D-glucofuranose, 0-3, 0-5, and 0-6 of which coordinate with the iodine atom of the reagent. There is evidence for two types of tridentate complex (9 and 10), corresponding to 7 and 8, respectively, and their stability appears to be consistent with Bunton s findings, because neither can be converted into a dehydrated form. ... 

Nal in acetone added to a soln. of bis-[3-0-(chloromethylsulfenyl chloride)- ,2 5,6-di-isopropylidene-ot-D-glucofuranose] disulfide in chloroform, and the product isolated after 10 min. ->l,2 5,6-di-0-isopropylidene- -D-glucofuranose 3-dilorothio-formate. Y 53%. B. S. Shasha and W. M. Doane, Carbohyd. Res. 16, 145 (1971). 

Studies of mono- and di-nucleotides using n.m.r. spectroscopy have reported chemical shifts and coupling constants. Both and n.m.r. spectroscopy were used to examine the stereoisomeric spirophosphoranes obtained by the joint action of tris(dimethyIamino)phosphine and carbon tetrachloride on 3-0-benzyl-l, 2-O-isopropylidene-ot-D-gluco- and -allo-furanose (see Vol. 9, p. 47), and, in conjunction with n.m.r. spectroscopy, the stereochemistries of 1,2-substituted 6-deoxy-6-halogeno-D-glucofuranose 3,5-phosphates. ... 

C. 1,2 5,6-Di-0-isopropylidene-3-0(2,3,4-trideoxy-ot-L-gr/ycero-hex-2-enopyranosyl)-a-D-glucofuranose (9) [21] (Scheme 12)... 

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