Bromide ion → beta-D-Ribofuranosyl bromide, 2,3,5-triacetate

HRID 259639

Reaktionsgleichung

Reaktionsgleichung von HRID 259639
C(O[C@@H:5]1[O:17][C@H:16]([CH2:18][O:19][C:20](=[O:22])[CH3:21])[C@@H:11]([O:12][C:13](=[O:15])[CH3:14])[C@H:6]1[O:7][C:8](=[O:10])[CH3:9])(=O)C.[Br-:23]>C1C=CC=CC=1.[N+](C)([O-])=O.C(OCC)(=O)C>[C:8]([O:7][C@@H:6]1[C@H:11]([O:12][C:13](=[O:15])[CH3:14])[C@@H:16]([CH2:18][O:19][C:20](=[O:22])[CH3:21])[O:17][C@H:5]1[Br:23])(=[O:10])[CH3:9]

Komponenten

6

Edukt 2

HCID 259Bromide ion2×HCID 830641,2,3,5-Tetraacetyl-beta-D-ribofuranose

Produkt 1

HCID 54432078beta-D-Ribofuranosyl bromide, 2,3,5-triacetate

Reagenzien, Katalysatoren, Lösungsmittel 3

HCID 241BenzeneLösungsmittelHCID 6375NitromethaneLösungsmittel2×HCID 8857Ethyl AcetateLösungsmittel

Versuchsvorschrift

A solution of 10 g of 5,6-O-isopropylidene- 1,2'3,6'-tetrakis-N-(trifluoroacetyl)neamine (3) in 330 ml of benzene and 220 ml of nitromethane is heated to boiling and 110 ml of distillate collected. 2,3,5-Tri-O-acetyl-β-D-ribofuranosyl bromide is prepared from 16.5 g of 1,2,3,5-tetra-O-acetyl-β-D-ribofuranose, as described above. The bromide is dissolved in 30 ml of nitromethane. One third of this solution and 7 g of mercuric cyanide is added to the original reaction mixture. The mixture is heated to reflux. Two similar additions of bromide and mercuric cyanide are made after 1 and 2 hours of reflux. The mixture is refluxed a final hour. The cooled reaction mixture is diluted with 750 ml of ethyl acetate and extracted with two 500 ml portions of 5% KHCO3 solution. The organic layer is washed with brine and filtered through Na2SO4. The solvent is evaporated under vacuum. The residue is chromatographed over 1 kg of silica gel, and eluted with chloroform-methanol (20:1). Fractions of 50 ml are collected and monitored by tlc. Fractions 1-30 contain fast moving impurities and are discarded. Fractions 30-40 (27A) weigh 13.4 g. while fractions 41-48 (27B) weigh 3.23 g. A 12.4 g portion of 27A is rechromatographed over 1 kg of silica gel using chloroform-methanol (30:1) for elution. The center cut based on tlc of the fractions is combined and evaporated to give 6.66 g of blocked analog (12β). CMR data, after removal of the blocking group as described infra, shows this compound to be chiefly the 3' β isomer.

Aufarbeitung

  1. temperatureThe mixture is heated to reflux
  2. customafter 1 and 2 hours
  3. temperatureof reflux
  4. temperatureThe mixture is refluxed a final hour
  5. customThe cooled reaction mixture
  6. extractionextracted with two 500 ml portions of 5% KHCO3 solution
  7. washThe organic layer is washed with brine
  8. filtrationfiltered through Na2SO4
  9. customThe solvent is evaporated under vacuum
  10. customThe residue is chromatographed over 1 kg of silica gel
  11. washeluted with chloroform-methanol (20:1)
  12. customFractions of 50 ml are collected
  13. customA 12.4 g portion of 27A is rechromatographed over 1 kg of silica gel
  14. washfor elution
  15. customevaporated

Quellen und Nachweise

ORD-Eintrag
ord-b8d4d30962614481853bdde59413f275
Quelldatensatz
uspto-grants-1977_07
Patentnummer
US04038478

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