2,4,6-Trimethylpyridine → 2-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl)-beta-D-galactopyranoside

HRID 653321Notes

Reaction equation

HRID 653321 reaction equation
Br[C@@:2]1([O:40][C@H:39]([CH2:41][O:42][C:43](=[O:45])[CH3:44])[C@H:14]([O:15][CH:16]2[O:33][C@H:32]([CH2:34][O:35][C:36](=[O:38])[CH3:37])[C@H:27]([O:28][C:29](=[O:31])[CH3:30])[C@H:22]([O:23][C:24](=[O:26])[CH3:25])[C@H:17]2[O:18][C:19](=[O:21])[CH3:20])[C@H:9]([O:10][C:11](=[O:13])[CH3:12])[C@H:4]1[O:5][C:6](=[O:8])[CH3:7])O.CC1C=C(C)C=C(C)N=1.[Br:55][CH2:56][CH2:57][OH:58]>C(Cl)Cl.FC(F)(F)S([O-])(=O)=O.[Ag+]>[C:6]([O:5][C@@H:4]1[C@@H:9]([O:10][C:11](=[O:13])[CH3:12])[C@@H:14]([O:15][C@H:16]2[O:33][C@H:32]([CH2:34][O:35][C:36](=[O:38])[CH3:37])[C@H:27]([O:28][C:29](=[O:31])[CH3:30])[C@H:22]([O:23][C:24](=[O:26])[CH3:25])[C@H:17]2[O:18][C:19](=[O:21])[CH3:20])[C@@H:39]([CH2:41][O:42][C:43](=[O:45])[CH3:44])[O:40][C@H:2]1[O:58][CH2:57][CH2:56][Br:55])(=[O:8])[CH3:7]

Participants

6

Reactant 3

HCID 79532,4,6-TrimethylpyridineHCID 108982-BromoethanolHCID 543253951-bromo-2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-D-galactopyranosyl)-alpha-D-galactopyranose

Product 1

HCID 228870902-Bromoethyl 2,3,6-tri-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl)-beta-D-galactopyranosideYield 77%

Reagents, catalysts & solvents 2

HCID 76223Silver(I) trifluoromethanesulfonateCatalystHCID 6344DichloromethaneSolvent2×

Procedure

A solution of the crude acetobromo sugar 49 (20.5 g; 29.3 mmol) in dry methylene chloride (100 ml) was added dropwise (ca 20 min) to a cold (-78°) solution of silver trifluoromethanesulfonate (nonpurified, commercial material; 10.3 g; 40 mmol), 2,4,6-tri-methylpyridine (3.6 g; 30 mmol) and 2-bromoethanol (17.5 g; 140 mmol) in methylene chloride (250 ml) under nitrogen. The reaction mixture was stirred in the dark for 23 h during which time it had reached room temperature. The yellowish-white precipitate, that had formed, was removed and the resulting colorless solution was washed consecutively with 1M hydrochloric acid, water, saturated sodium hydrogen carbonate solution and water. Drying (sodium sulfate), filtration and evaporation gave a residue which crystallized spontaneously. Recrystallization from ethyl acetate, followed by evaporation of the mother liquor and recrystallization from methanol, gave a total of 16.6 g (77%) of the title compound 15. Melting point and optical rotation are shown in Table 1 and the 13C- and 1H-NMR data are shown in Table 2 and 3 , respectively.

Workup

  1. customhad reached room temperature
  2. customThe yellowish-white precipitate, that had formed
  3. customwas removed
  4. washthe resulting colorless solution was washed consecutively with 1M hydrochloric acid, water, saturated sodium hydrogen carbonate solution and water
  5. customDrying
  6. filtration(sodium sulfate), filtration and evaporation
  7. customgave a residue which
  8. customcrystallized spontaneously
  9. customRecrystallization from ethyl acetate
  10. customfollowed by evaporation of the mother liquor and recrystallization from methanol

Sources & evidence

ORD record
ord-c091bbdad3ac476da739b5e4abfc978b
Source dataset
uspto-grants-1987_06
Patent number
US04675392

Reaction notes

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