D-Xylo-hexofuranose

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. 

Cyclohexan 2-Oxo-l,l,3,3-tetrakis-[hydroxymethyl]- VII/2b, 1462 6-Deoxy-a-D-galactopyranosid Methyl-3,4-O-isopropyliden-E19a, 153 (6-1 -> H) 5-Deoxy-a-D-xylo-hexofuranose ... 

O-isopropylidene-a-D-xylo-hexofuranose and 6-deoxy-l, 2-O-iso-propylidene-)8-L-idofuranose in 62 and 30% yield, respectively. Various conditions were tested, " without success, for raising the yield of 5-deoxy-l,2-0-isopropylidene-a-D-xt/io-hexofuranose the yield was significantly lowered (about 30%) when the hydride reduction was performed in tetrahydrofuran. A mechanism was proposed for formation of the two products namely, that formation of 6-deoxy-... 

Sugar herbicide RE 39571, 5,6-dideoxy-l,2-0-(l-methylethylidene)-3-0-(2-methylphenylmethyl)-a-D-xylo-hexofuranose (Figure 1), a representative of a novel series of chiral grass herbicides, has been demonstrated in our laboratories to possess a high level of preemergence herbicidal activity against grassy weeds with safety on soybeans, cotton, peanuts, and several other broadleaf crops. This herbicide has also been demonstrated to possess some broadleaf weed activity. 

The addition of phosphines to double bonds of carbohydrates has been demonstrated for the first time with the alkene 79 (R = R = H).142 Under ultraviolet light, phosphine itself gave what was believed to be a mixture of (5,6-dideoxy-l,2-0-isopropylidene-a-D-xy/o-hexofura-nose-6-yl)phosphine and bis(5,6-dideoxy-l,2-0-isopropylidene-a-D-xylo - hexofuranose - 6 - yl)phosphine, which were characterized as oxidized products and, under similar conditions, phenylphosphine gave phenyl (5,6-dideoxy-l,2-0-isopropylidene-a-D-xy(o-hexofura-nose-6-yl)phosphine, which was isolated in 75% yield as its oxide.142... 

Cyclization of 5,6-dideoxv-6-nitro-D-xylo-hexofuranose led to a mixture of myo- and epi-isomers (43) which were separated and converted to the corresponding amino compounds.Examples of the use of the Ferrier reaction for preparing cyclitols and amino-cyclitols from D-glucose and D-glucosamine have been published, e.g., (44)- (45).52... 

Tetra-Ac 1,2,5,6-Tetra-0-acetyl-3-deoxy-D-xylo-hexofuranose [23655-60-9]... 

Following Bock s observation with the only substrate that had been converted quantitatively, 5-deoxy-D-xylo-hexofuranose ( 5-deoxy-D-glucose , 59), it was discovered [83] that any derivative of D-glucose not bearing a free hydroxyl function at C-5, such as the 5-azidodeoxy (71), the 5-deoxyfluoro (73), and the 5-0-... 

The addition of iodine trifluoroacetate (produced by reaction of iodine with silver trifluoroacetate) to unsaturated carbohydrates has been investigated.134 Treatment of 5,6-dideoxy-l,2-0-isopropylidene-a-D-xylo-hex-5-enofuranose (89) with silver trifluoroacetate and iodine in acetonitrile gave 3,6-anhydro-5-deoxy-5-iodo-l,2-0-iso-propylidene-a-D-gluco(and /3-L-ido)furanose (91) and 5-deoxy-5-iodo-l,2-0-isopropylidene-6-0-(trifluoroacetyl)-o -D-gluco(and/or /3-L-ido)-furanose (92), with the former preponderating. Component 91 was converted into 3,6-anhydro-5-deoxy-l,2-0-isopropylidene-a-D-xj/io-hexofuranose (94) by hydrogenation over Raney nickel (see also, Section III,3 p. 299), and component 92 was converted into 5-deoxy-l,2-0-isopropylidene-a-D-xy/o-hexofuranose (95) by treat-... 

Hexofuranose, 3,6-anhydro-5-deoxy-l,2-O-isopropylidene-a-D-xylo-, 241 —, 5 - deoxy -1,2 - O - isopropylidene - a - D -xylo-, 275... 

Addition of nitryl iodide to 3-0-acetyl-5,6-dideoxy-l,2-0-iso-propylidene-a-D-xylo-hex-5-enofuranose, followed by dehydroiodina-tion of the product with sodium hydrogen carbonate in refluxing benzene, furnished910 the same 5,6-unsaturated 6-nitro hexose derivative (182, see Section IV,2c, p. 127) that had been synthesized previously by sequential acetylation and dehydroacetylation of 88. Borohydride reduction of 182 gave910 5,6-dideoxy-l,2-0-isopropyl-idene-6-nitro-a-D-xt/lo-hexofuranose. 

J. M. J. Tronchet and B. Gentile, 3-C(Acylm6thylbne)-3-desoxy-l,2 5,6-di-0-isopropylidbne-a-D-ribo- et -xylo-hexofuranoses, Carbohydr. Res. 44 23 (1975). 

The favored conformations of all eight l,2 5,6-di-0-isopropylidene-D-hexofuranoses have been evaluated by means of a computer-assisted, n.m.r. technique.102 It was demonstrated that the furanoid conformation is determined by the joint effects of the 1,2-O-isopropylidene part and the 5,6- tail unit. The ribo and lyxo structures were found to approximate to envelope conformations, whereas the arabino- and xylo-furanoses are less distorted, and approximate to twist conformers. 

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