Acetic Anhydride → Tri-O-acetyl-D-glucal

HRID 1489139Notes

Reaction equation

HRID 1489139 reaction equation
[CH3:1][C:2]([O:4][CH2:5][C@H:6]1[O:11][CH:10]=[CH:9][C@H:8]([O:12][C:13]([CH3:15])=[O:14])[C@@H:7]1[O:16][C@H:17]1[O:22][C@H:21]([CH2:23][O:24][C:25]([CH3:27])=[O:26])[C@@H:20]([O:28][C:29]([CH3:31])=[O:30])[C@H:19]([O:32][C:33]([CH3:35])=[O:34])[C@H:18]1[O:36][C:37]([CH3:39])=[O:38])=[O:3].C(O)[C@H]1O[C@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@@H]1O.O.C(OC(=O)C)(=O)C.Br.C(O)(=O)C.C([O-])(=O)C.[Na+]>[Zn].C(O)(=O)C.O>[CH3:1][C:2]([O:4][CH2:5][C@H:6]1[O:11][CH:10]=[CH:9][C@H:8]([O:12][C:13]([CH3:15])=[O:14])[C@@H:7]1[O:16][C@H:17]1[O:22][C@H:21]([CH2:23][O:24][C:25]([CH3:27])=[O:26])[C@@H:20]([O:28][C:29]([CH3:31])=[O:30])[C@H:19]([O:32][C:33]([CH3:35])=[O:34])[C@H:18]1[O:36][C:37]([CH3:39])=[O:38])=[O:3].[C:13]([O:12][C@H:8]1[C@H:7]([O:16][C:17](=[O:22])[CH3:18])[C@@H:6]([CH2:5][O:4][C:2](=[O:3])[CH3:1])[O:11][CH:10]=[CH:9]1)(=[O:14])[CH3:15]

Participants

10

Reactant 5

HCID 7918Acetic AnhydrideHCID 517045Sodium AcetateHCID 2723821(2R,3S,4S,5R,6R)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R,6R)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol;hydrateHCID 21893785Acetic Acid Mixture with Hydrobromic Acid2×HCID 90474636hexa-O-acetyl maltal

Product 2

HCID 688303Tri-O-acetyl-D-glucalYield 88%HCID 90474636hexa-O-acetyl maltalYield 86%

Reagents, catalysts & solvents 3

HCID 23994ZincCatalystHCID 176Acetic AcidSolvent2×HCID 962WaterSolvent

Procedure

The procedure used to synthesize hexa-O-acetyl maltal (not commercially available) is described below. This procedure has the advantage of using the same solvent for the entire workup. Maltose monohydrate (1.000 g 90% maltose, 10% glucose and maltatriose) was suspended in a solution of acetic acid (10 mL) and acetic anhydride (2.833 g, 10.0 equiv) and 1.000 g 31% HBr/acetic acid solution added. The reaction mixture was allowed to stir for 1 h, after which 9.000 g more 31% HBr/acetic acid solution was added and allowed to stir overnight. The reaction mixture was then poured into a suspension containing pulverized CuSO4.5H2O (0.182 g), zinc (7.290 g), water (10 mL), sodium acetate (5.470 g), and acetic acid (5 mL) and the resultant reaction mixture was stirred vigorously for 1.5 h. The solution was then filtered and the solid washed with ethyl acetate (100 mL) and water (100 mL). The organic layer of the filtrate was then washed with NaHCO3 (100 mL) and brine (50 mL), dried (Na2 SO4), filtered and the solvent removed under reduced pressure to provide a colorless oil which was purified by silica gel chromatography (50% ethyl acetate/hexanes) to give hexa-O-acetyl-maltal (1.210 g, 86%) as a colorless solid and tri-O-acetyl-D-glucal (0.132 g, 88%) as a colorless oil. Regarding the maltose starting material, a more pure commercial sample would be preferred, obviating the need for the aforementioned chromatographic separation.

Workup

  1. additionadded
  2. stirringto stir overnight
  3. additionThe reaction mixture was then poured into a suspension
  4. additioncontaining
  5. customthe resultant reaction mixture
  6. stirringwas stirred vigorously for 1.5 h
  7. filtrationThe solution was then filtered
  8. washthe solid washed with ethyl acetate (100 mL) and water (100 mL)
  9. washThe organic layer of the filtrate was then washed with NaHCO3 (100 mL) and brine (50 mL)
  10. customdried (Na2 SO4)
  11. filtrationfiltered
  12. customthe solvent removed under reduced pressure
  13. customto provide a colorless oil which
  14. customwas purified by silica gel chromatography (50% ethyl acetate/hexanes)

Sources & evidence

ORD record
ord-10b64d6a10a8430b8e5ac94de3042429
Source dataset
uspto-grants-1997_10
Patent number
US05677286

Reaction notes

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