L,2:5,6-Di-0-isopropylidene-D-glucofuranose

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

The reaction of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49), with phosphorus pentachloride was reported in 1926 by Allison and Hixon (I) who formulated the product as 3-chloro-3-deoxy-l,2 5,6-di-0-isopro-pylidene-D-glucofuranose (2% yield). A reinvestigation (93) of the... 

Fukuda et al. used both a nitroxide-mediated polymerization as well as ATRP to polymerize a sugar containing methacrylate monomer and produce water-soluble glycopolymers however, only ATRP was used to prepare block copolymers [202,203]. The ATRP of 3-0-methacryloyl-l,2 5,6-di-0-isopropylidene-D-glucofuranose (MAIpGlc, Fig.27) was carried out to determine the characteristics of the homopolymerization. It was found that the relationship between the concentration of initiator and the rate of polymerization was not a simple first-... 

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). 

II) From Vinylic Ethers.—The base-catalyzed elimination of certain tosyloxy functions in carbohydrates was demonstrated as early as 1922 by Freudenberg and Brauns.118 From the reaction of 1,2 3,6-dHO-isopropyl-idene-3-O-p-tolylsulfonyl-D-glucofuranose (16) with anhydrous hydrazine, they obtained, in addition to the 3-hydrazino derivative, 3-deoxy-l, 2 5,6-di-0-isopropylidene-D-erj/(Aro-hex-3-enofuranose (17). Hydrogenation of... 

On the other hand, diacetone D-glucose was transformed to (-)- and (+)-sesbanimide A via the open chain derivative 3-0-benzyl-D-glucose diethyldithioacetal 17, which was prepared by hydrolysis of 3-C -benzyl-l,2 5,6-di-C -isopropylidene-D-glucofuranose (16) and subsequent treatment with ethanethiol in the presence of acid (Scheme 3)4 Acetonation of 17 under kinetic control followed by methylenation with dibromomethane afforded the key intermediate 1,3-dioxane 18. Deprotection of the dithioacetal unit in 18 followed by... 

Di-0-isopropylidene- -D-glucofuranose stirred 6 hrs. with 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl bromide and Ag-salicylate in tetrahydrofuran -> 3,4,6-tri-0-acetyl-l,2-0-[l-(l,2 5,6-di-0-isopropylidene-a-D-glucofuranos-3-yl)ethy-lidene]-a-D-glucopyranose. Y 74%. F. e. s. G. Wulff and W. Kruger, Carbohyd. Res. 19, 139 (1971). 

In l,2 5,6-di-0-isopropylidene-a-D-glucofuranose five of the six funaional groups of glucose are protected. The free 3-hydroxyl group is a popular starting point in synthesis. It... 

Of particular value, was the reagent s ability to oxidize a hydroxyl group attached directly to a furanoid ring (6, 7, 46), as is illustrated by the conversion of l,2 5,6-di-0-isopropylidene-a-D-glucofuranose into l,2 5,6-di-0-isopropylidene-a-D-n o-hexofuranos-3-ulose (1). The follow-... 

The mass spectra of methyl 3-deoxy-p-v-tkreo-pentopyrano-side, methyl 4-deoxy-j3-T>-thieo-pentopyranoside, and 5-deoxy-fi-D-xylo-furanoside are discussed and compared fragmentation paths are sufficiently different to allow identification on the basis of their mass spectra. On the other hand, the mass spectra of methyl 2- and 3-deoxy-5-O-methyl-f3-i>-erythro-pentofuranosides do not exhibit fragmentation differences. The mass spectra of 3-deoxy-l,2 5,6-di-O-isopropylidene -d-xylo - hexofuranose, 5- deoxy -1,2-0-isopropylidene-D-xy o-hexofuranose, and 6-deoxy-l,2-0-iso-propylidene-D-glucofuranose show prominent differences, even between the 5- and 6-deoxy isomers. The interpretation of the spectra was aided by metastable-ion peaks, mass spectra of DzO-exchanged analogs, and the mass spectrum of an O-isopropylidene derivative prepared with acetone-d6. 

Solid Acid-Catalyzed Selective Deprotection of l,2 5,6-Di-0-isopropylidene-a-D-glucofuranose (102)... 

The purpose of this study was to explore the introduction of an OZT moiety onto the specific C-3 site of both l,2 5,6-di-0-isopropylidene-a-D-glucofuranose and 1,2 4,5-di-0-isopropylidene-p-D-fructopyranose, taking advantage of the well-defined frame of both carbohydrate structures to generate all possible OZT-isomers. These spiroheterocyclic structures could be constructed according to a simplified sequence based on a key stereoselective approach from uloses via epoxides or aziridines (Scheme 16). 

When comparing these results with those previously obtained using carbohydrate-based vinyl ethers as chiral dienophiles, this improved facial diastereoselectivity to heterodienes under similar conditions is noteworthy.81 The efficient chiral transfer in the second example might mostly be attributed to the specific architecture of the l,2 5,6-di-0-isopropylidene-a-D-glucofuranose moiety.Those findings open the way to develop well-defined spiro-carbohydrate templates towards improved auxiliaries for chirality transfer in a wide range of syntheses. 

The selective introduction of fluorine into a furanose ring was demonstrated by the reaction of TASF with l,2 5,6-di-0-isopropylidene-3-O-trifluoromethanesulfonyl-a-D-allofuranose (12) which gave a 66% yield of 3-deoxy-3-fluoro-l,2 5,6-di-0-isopropylldene-a-D-glucofuranose (2. The isomeric triflate 13,... 

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