Phosphorus tribromide → 21-Bromo-20-methyl-1alpha,3beta-bis(methoxycarbonyloxy)pregna-5,7-diene

HRID 1587607Notes

Reaction equation

HRID 1587607 reaction equation
[CH3:1][CH:2]([C@@H:5]1[C@:22]2([CH3:23])[C@H:8]([C:9]3[C@H:19]([CH2:20][CH2:21]2)[C@:17]2([CH3:18])[C:12]([CH2:13][C@@H:14]([O:29][C:30]([O:32][CH3:33])=[O:31])[CH2:15][C@@H:16]2[O:24][C:25]([O:27][CH3:28])=[O:26])=[CH:11][CH:10]=3)[CH2:7][CH2:6]1)[CH2:3]O.P(Br)(Br)[Br:35]>N1C=CC=CC=1>[Br:35][CH2:3][CH:2]([CH3:1])[C@@H:5]1[C@:22]2([CH3:23])[C@H:8]([C:9]3[C@H:19]([CH2:20][CH2:21]2)[C@:17]2([CH3:18])[C:12]([CH2:13][C@@H:14]([O:29][C:30]([O:32][CH3:33])=[O:31])[CH2:15][C@@H:16]2[O:24][C:25]([O:27][CH3:28])=[O:26])=[CH:11][CH:10]=3)[CH2:7][CH2:6]1

Participants

4

Reactant 2

HCID 24614Phosphorus tribromideHCID 6778866020-Methyl-1alpha,3beta-bis(methoxycarbonyloxy)pregna-5,7-dien-21-ol

Product 1

HCID 6778853721-Bromo-20-methyl-1alpha,3beta-bis(methoxycarbonyloxy)pregna-5,7-diene

Reagents, catalysts & solvents 1

HCID 1049PyridineSolvent

Procedure

IN 1 ml of pyridine was dissolved 75 mg of 20-methyl-1α,3β-bis(methoxycarbonyloxy)pregna-5,7-dien-21 -ol and, then, under ice-cooling, 0.05 ml of phosphorus tribromide was added. The mixture was stirred at the same temperature for 15 minutes. The reaction mixture was then poured into ice water and extracted with diethyl ether. The extract was washed with aqueous sodium hydrogen carbonate solution and aqueous sodium chloride solution, dried over anhydrous sodium sulfate and concentrated. The residue was purified by silica gel column chromatography to give 53 mg of 21-bromo-20-methyl-1α,3β-bis(methoxycarbonyloxy)pregna-5,7-diene.

Workup

  1. temperatureunder ice-cooling
  2. extractionextracted with diethyl ether
  3. washThe extract was washed with aqueous sodium hydrogen carbonate solution and aqueous sodium chloride solution
  4. dry with materialdried over anhydrous sodium sulfate
  5. concentrationconcentrated
  6. customThe residue was purified by silica gel column chromatography

Sources & evidence

ORD record
ord-cf0df3ea6df74116bf53e860d887e825
Source dataset
uspto-grants-1993_06
Patent number
US05218109

Reaction notes

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