Xylos

Moderate in vivo antiherpes vims activity was demonstrated by 9-P-Dxylofuranosylguanine [27462-39-1] (xylo-G, 38), C qH N O, and the 5 -mono-and 3, 5 -cycHc phosphates of (38), although none was as active as ara-A (89). Generally, guanine base-modified analogues of acyclovir are less active than acyclovir because they are not readily phosphorylated by herpes thymidine kinase. 

Xylo-chinoh n. xyloquinol. hinon, n. zylo-quinone. 

The discrepancy between the behavior of arabinose- and xylose-3, 5-(hydrogen phosphates) probably reflects the difference which exists in the steric arrangement of these two cyclic phosphodiesters. In the xylo-furanose derivative (89), the hydroxyl group on C-3 and the primary hydroxyl group are cis the cyclic phosphate is easily formed and perfectly strainless. In arabinofuranose these same groups are in position trans and, although an apparently strainless molecule can be constructed from models, it is probable that in this case the main ring of the compound will be that formed by the phosphodiester, with a concomitant tendency for the compound to assume the aldehydo form. Objection to... 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

It was of interest to determine whether glycosides of 6-deoxy-D-xylo-hex-5-enopyranose were susceptible to enzyme hydrolysis by / -glucosi-dase. Since aromatic glucosides are hydrolyzed by this enzyme at a much faster rate than aliphatic glycosides, phenyl 6-deoxy-/ -D-rt/Zo-hex-5-enopyranoside (18) was prepared (20). Phenyl / -D-glucopyranoside was converted to the 6-tosylate by selective esterification and then, by conventional procedures, transformed to phenyl 2,3,4-tri-0-acetyl-6-deoxy-... 

Acetyl-5-deoxy-5-iodo-l, 2-O-isopropylidene-p - l - arabinofuranose (38). Acetylation of 5-deoxy-5-iodo-l,2-0-isopropylidene-/ -L-arabino-furanose (37) (27) in pyridine as described above for the D-xylo-isomer afforded the 3-acetate (38) as a colorless sirup which did not crystallize. [ ]D24 + 13.7° (c, 3.5). Anal Calcd. for C10H15IO5 C, 35.1 H, 4.4. Found C, 35.0 H, 4.5. 

Product 15 was eventually transformed into methyl 4,6-dideoxy-a-D-xylo-hexopyranoside by reductive desulfurization. A related reaction is the formation (41) of the 4-thiocyanato derivative 17 in 47% yield from 16 (140°C., 22 hours in N,N-dimethylformamide). This has been suggested as a good route to 4-deoxy-D-xt/Zo-hexoses compared with the available methods (43). 

Another internal acetal, methyl 2-0-benzoyl-3,4-0-benzylidene-/ -D-arabinopyranoside 103 (84), behaves in an analogous manner, except that the isomeric 4-bromo (104) and 3-bromo (105) benzoate derivatives are formed in a ratio of 1 1. The identity of 104 (l-xylo) can be deduced from its mode of formation from a presumed benzoxonium ion (106)... 

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. 

Hexose 6-phosphate, 3-deoxy-D-nho Hexose 6-phosphate, S-deoxy-D-xylo-Hexose, phosphate esters of... 

Methyl 5-deoxy-D-xt/Zo-furanoside. . 207 Methyl 6-deoxy-a-D-glucopyranoside 126 Methyl 4-deoxy-a-D-xylo-... 

R,3S,45)-5-Benzyloxy-l-(l,3-dioxolan-2-yl)-3,4-bis(niethoxyinethoxy)-2-pentanol 6-0-Benzyl-2-deoxy-4,5-0-bis(methoxymcthyl)-L-xylo-hexose, ethylene acetal] syn,syn-l2. R = (l,3-dioxolan-2-yl)methyl Typical Procedure89 ... 

R)-2-Hydroxy-3-thiopropanal (Table 5), which could not be isolated from the reaction mixture, can be directly converted into 6-thio-D-wnimo-2-hexulose (7%) and 6-thio-L-xylo-2-hexulose (93 %) via rabbit muscle aldolase catalyzed condensation with dihydroxyacetonephos-phate28. 

Another reason is that xylo-oligosaccharides of defined structure are very important substrates that serve as model compounds for the optimization of hydrolytic processes and in enzymic assays. The enormous development... 

Otriven (CIBA Vision) Pertix Hommel (Hommel) Rapako (Truw) schnupfen endrine (Asche) Stas Nasenspray (Stada) Xylo-COMOD (Ursapharm)... 

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