Of 1,2-0-isopropylidene-D-glucofuranose

This review will be limited to a discussion of the structures and reactions of the aldehydes obtained from oxidation of cyclic carbohydrate derivatives. Such products as that from the oxidation of 1,2-0-isopropylidene-D-glucofuranose, which is a monoaldehyde, will not be dealt with. A monosaccharide derivative will normally give rise to a dialdehyde, a disaccharide derivative to two dialdehyde units linked together (or a tetra-aldehyde), and a polysaccharide will give a dialdehyde polymer (a polyaldehyde). All of these classes of compounds will be discussed. 

The oxidation of 1,2-O-isopropylidene-D-glucofuranose with lead tetraacetate was found by Criegee to yield formaldehyde,43 which confirmed the presence of a furanose ring in the sugar derivative. The major oxidation fragment, l,2-0-isopropylidene-5-oZde/q/do-D-a yZo-pentodialdose, was characterized subsequently by Iwadare,88 and has recently been shown to crys-... 

A practical synthesis of nojirimycin from D-glucose has been described, giving an overall yield of 50% from 1,2-0-isopropylidene-D-glucofuranose oxidation of this compound with tributyltin oxide/ bromine selectively gave the 5-keto sugar, which was then converted to the 5-amino-sugar and hence to nojirimycin. The isolation of... 

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. 

Chiral 18-crown-6 derivatives incorporating both one and two L-glyceralde-hyde dithioethylacetal residues have also been reported (128) recently. Also, a benzo-18-crown-6 ring has been appended (129) to the C-5 and C-6 positions of 1,2-0-isopropylidene-3-(9-methyl-a-D-glucofuranose. 

All of these examples illustrate the complexing ability of an ax-eq-ax sequence of oxygen atoms on a six-membered or of a cis-cis sequence on a five-membered ring. Attempts have been made to find other complexing sites on sugar molecules but with little success. The 0-3, 0-5, and 0-6 arrangement of hexofuranoses, which allows the ready formation of tri-dentate periodate (IS), and orthoformate esters (19), does not form stable complexes with metal ions. In solution the side-chain of 1,2-0-isopropylidene-a-D-glucofuranose (13) is in the extended zig-zag form... 

The only recorded examples of carbohydrate trithiocarbonates were prepared by McSweeney and Wiggins in 1951. These authors caused 5,6-an-hydro-1,2-0-isopropylidene-n-glucofuranose to react with carbon disulhde and potassimn hydroxide in boiling methanol, and allegedly obtained 1,2-0-isopropylidene-5,6-dithio-n-glucofuranose 5,6-trithiocarbonate (see p. 102). The related derivatives from 5,6-anhydro-l, 3 2,4-di-0-ethyUdene-D-glucitol and 5,6-anhydro-l, 2 3,4-di-O-isopropylidene-D-mannitol were also synthesized, in a similar manner. All three esters could be desulfurized with Raney nickel to the corresponding dideoxy compounds. 

The relative reactivity toward sodium of the hydroxyl groups at the various carbon atoms of a sugar has been exploited in order to prepare selected derivatives. By the addition of one molar equivalent of sodium to 4,5-0-isopropylidene-D-fucose dimethyl acetal in ethyl ether, followed by benzyl chloride, Schmidt and Wernicke were able to isolate a 42 % yield of 2-0-benzyl-4,5-0-isopropylidene-D-fucose dimethyl acetal. Freudenberg and Noe reacted molar equivalents of 1,2-0-isopropylidene-a-D-glucofuranose and sodium in boiUng dioxane. Subsequent reaction with benzyl chloride, and acetylation, gave a 29 % yield of crystalline 5,6-di-0-acetyl-3-0-benzyl-1,2-0-isopropylidene-a-D-glucose. 

The reaction of 1,2-0-isopropylidene-a-D-glucofuranose phosphite (20) with (17) or hexafluorobiacetyl (22) gave (21) and (23) respectively in almost quantitative yield and the products were characterized by elemental analysis and multi-nuclear ( C, F, P) NMR. i... 

One of the earliest examples was the isolation of an unexpected pentaacetate after treatment of 1,2-0-isopropylidene-a-D-glucofuranose with acetic anhydride and zinc chloride. These reagents had effectively produced the acetylium ion (8). The product was subsequently character-... 

The first synthesis of a thio sugar by epoxide scission to be reported was the preparation of 1,2-0-isopropylidene-6-thio-D-glucose (67, R = H) from 5,6-anhydro-l,2-0-isopropylidene-a-D-glucofuranose (66) by the action of hydrogen sulfide. The product was isolated as the crystalUne... 

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