Xylofuranose

Reaction of 3-aminopropanol with an a and [3 mixture of 5-bromo-5-deoxy-2-xylofuranose (25) and 5-(9-tosyl-D-lyxofuranose in MeCN afforded anomeric mixtures of trihydroxypyrido[2,l-Zi]l,3]oxazines 20, 21 and 22-24, respectively (99T6759, 99T14251). 

Reaction of 1,3-propanediamine and a mixture of a and isomers of 5-bromo-5-deoxy-D-xylofuranose in H2O for 10 min gave 1 R-(la,8p,9a9aa)-7,8,9-trihydroxyperhydropyrido[l, 2-u]pyrimidine (112, R = H) in 27% yield (99T6759). Reaction of 5-bromo-5-deoxy-D-xylofuranose and A -methyl-1,3-propanediamine in H2O at room temperature afforded a 5 1 mixture of 1-methyl 117 and 5-methyl 118 derivatives of 7,8,9-trihydroxyperhydropyr-ido[l, 2-u]pyrimidine 112 (R = H). When this reaction was carried out in the presence of 3 moles of NEts the product ratio of 117 to 118 was 1 2. The influence of NEt3 on the product ratio may be a consequence of it scavenging HBr and freeing the more basic and more nucleophilic methylamino group for participation in the displacement reaction. 

Acetyl-5-deoxy-l,2-0-isopropylidene-[3-iJ - threo - pent - 4 - enofura-nose (34). (1) From 3-0-acetyl-5-deoxy-5-iodo-1,2-0-isopropylidene- -d-xylofuranose (31). Anhydrous silver fluoride (7.5 grams) was added to a solution of 7.2 grams 26 in dry pyridine (50 ml.), and the mixture shaken at room temperature for 24 hours. The black reaction mixture was diluted with ether (50 ml.), and the supernatant liquid was decanted from the dark, inorganic residue. The residue was further extracted with ether (3 X 50 ml.) and the pyridine-ether solution partially decolorized... 

From 1,2-0-isopropylidene-3,5-di-0-tosyl-/ -d-xylofuranose (21) (29). Treating 29 with silver fluoride in pyridine and isolating as described above for the l-arabino isomer gave a 40% yield of 32 after a reaction time of 48 hours. The product had [ ]D25 — 14.9° and had an infrared spectrum identical with material prepared as above. 

From 5-deoxy-5-iodo-1,2-0-isopropylidene- -d-xylofuranose (30). A solution of 1.14 grams of 30 in pyridine (8.0 ml.) was shaken at room temperature with silver fluoride (2.0 grams). The reaction was slower than with the corresponding 5-tosylate (22) and was complete after 72 hours. The reaction mixture was processed as described above to give a pale yellow sirup which contained, in addition to 28, three minor components. Distillation afforded pure material (0.4 grams, 75%) identical with material prepared as above. 

From the reaction of 5-0-benzoyl-l,2-0-isopropylidene-o -D-en/t/iro-pentofuranos-3-ulose (prepared in 80% yield by oxidation of 5-0-benzoyl-l,2-0-isopropylidene- -D-xylofuranose (35,36) with ruthenium tetroxide) with an excess of diazomethane in methanol-ether, two main products (m.p. 44°-45°C. and 76°-77°C.), both epoxides, could be isolated by chromatography of the product on a silica column. An... 

O-isopropylidene-a-D-xylofuranose (CsHijO, 20037-27-4) see Stavudine isopropyl iodide... 

Scheme 1.18 Test reaction with xylofuranose-based phosphinooxathiane ligands.

Scheme 2.9 Cu-catalysed 1,4-addition of ZnEt2 to 2-cyclohexenone with thioether-alcohol ligands bearing xylofuranose backbone.

In 2000, Claver et al. reported the synthesis of novel chiral S/P ligands with a xylofuranose backbone. These thioether-phosphite ligands derived from carbohydrates were investigated for the rhodium-catalysed hydroformylation of styrene but, in spite of good conversions (>99%) combined with excellent... 

Scheme 10.4 Rh-catalysed hydroformylation of styrene with xylofuranose-derived thioether-phosphite ligands.

Ir(CO)2(aniline-dithiocarbamate) shows a moderate activity against Ehrlich ascites at 50 mg kg 1,704 The synthesis of air-unstable [Ir2(//-L)(cod)2], where H2L = RiSSH2(l,2-0-isopropylidene-2,5-dithio-a-D-ribofuranose, XySSH2(l,2-0-isopropylidene-3,5-dithio-a-Z)-xylofuranose), is described.705... 

Many polyhydroxylated quinolizidines <1995CRV1677>, frequently designed as azasugars, are powerful glycosidase inhibitors and therefore have potential therapeutic application. The 7-oxa-l-azabicyclo[2.2.1]heptane derivative 191, obtained from 3-0-benzyl-l,2-0-isopropylidene-l,5-pentadialdo-a-D-xylofuranose with... 

Figure 11.10 Comparison of extracted ion pyrograms of fragment ion m/z 217 of two samples collected from the paint surfaces of Universal Judgement and Stories of Holy Fathers (Monumental Cemetery of Pisa, Italy, painted by Buffalmacco, fourteenth century) with nitro cellulose, starch and arabic gum. 1, Unidentified compound 2, 1,2,3,5 tetrakis (O TMS) xylo furanose 3, tri (O TMS) levoglucosane 4, isomer of 1,2,3,5 tetrakis (O TMS) xylofuranose. Pyrogram obtained with a resistively heated filament at 60CPC in the presence of HMDS [30]...

S-glycofuranosyl dithiocarbamates with 5-nitro-2-pyridyl 2,3,4-tri-O-benzoyl-l-thio-P-D-glucopyranoside as an acceptor gives access to valuable 1,2-ds-linked furanosyl-1-thiopyranosides [498]. Recently, Bogusiak reported that perbenzylated S-benzothiazolyl glycosides of L-arabino, D-ribo and D-xylofuranose can be used as glycosyl donors (Scheme 4.91). ... 

Hz, Jfcu.h-i = 0 Hz (cis and trans relative to C-2). Also, a through-space coupling-constant was considered to be operative between Ftrans and H-5 in these compounds254,264 and a number of corresponding xylofuranoses.254... 

---