Water → 3alpha-Acetoxy-2beta-bromo-5alpha-pregnan-20-one

HRID 1606482Notes

Reaction equation

HRID 1606482 reaction equation
[OH:1][C@@H:2]1[C@@H:21]([Br:22])[CH2:20][C@@:19]2([CH3:23])[C@@H:4]([CH2:5][CH2:6][C@@H:7]3[C@@H:18]2[CH2:17][CH2:16][C@@:15]2([CH3:24])[C@H:8]3[CH2:9][CH2:10][C@@H:11]2[C:12](=[O:14])[CH3:13])[CH2:3]1.[C:25](OC(=O)C)(=[O:27])[CH3:26].O>N1C=CC=CC=1>[C:25]([O:1][C@@H:2]1[C@@H:21]([Br:22])[CH2:20][C@@:19]2([CH3:23])[C@@H:4]([CH2:5][CH2:6][C@@H:7]3[C@@H:18]2[CH2:17][CH2:16][C@@:15]2([CH3:24])[C@H:8]3[CH2:9][CH2:10][C@@H:11]2[C:12](=[O:14])[CH3:13])[CH2:3]1)(=[O:27])[CH3:26]

Participants

5

Reactant 3

HCID 962WaterHCID 7918Acetic AnhydrideHCID 572036952beta-Bromo-3alpha-hydroxy-5alpha-pregnan-20-one

Product 1

HCID 867332963alpha-Acetoxy-2beta-bromo-5alpha-pregnan-20-one

Reagents, catalysts & solvents 1

HCID 1049PyridineSolvent

Procedure

A solution of 3α-hydroxy-2β-bromo-5α-pregnan-20-one (8.5 g.) in pyridine (25 ml.) was treated with acetic anhydride (12.5 ml.), and the mixture was allowed to stand at room temperature overnight. The reaction mixture was poured into water and the product was extracted with methylene chloride. The extract was washed with water, dried (Na2SO4) and evaporated. A portion (582 mg.) of the residue (8.5 g.) was purified by preparative t.l.c. and crystallisation from iso-propyl ether to give 3α-acetoxy-2β-bromo-5α-pregnan-20-one (70 mg.), 142°-146°, [α]D + 120.9°.

Workup

  1. extractionthe product was extracted with methylene chloride
  2. washThe extract was washed with water
  3. dry with materialdried (Na2SO4)
  4. customevaporated
  5. customA portion (582 mg.) of the residue (8.5 g.) was purified by preparative t.l.c
  6. customand crystallisation from iso-propyl ether

Sources & evidence

ORD record
ord-8dd97b47fa164191b9ddef5a077ec623
Source dataset
uspto-grants-1976_04
Patent number
US03953429

Reaction notes

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