Acetic Anhydride → 1-[6-(4-Fluorophenyl)imidazo[2,1-b][1,3]oxazol-5-yl]ethanone

HRID 1925212Notes

Reaction equation

HRID 1925212 reaction equation
[F:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[N:9]=[C:10]3[N:14]([CH:15]=2)[CH:13]=[CH:12][O:11]3)=[CH:4][CH:3]=1.[C:16](OC(=O)C)(=[O:18])[CH3:17]>S(=O)(=O)(O)O>[F:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[N:9]=[C:10]3[N:14]([C:15]=2[C:16](=[O:18])[CH3:17])[CH:13]=[CH:12][O:11]3)=[CH:6][CH:7]=1

Participants

4

Reactant 2

HCID 7918Acetic AnhydrideHCID 574336106-(4-Fluorophenyl)-imidazo[2,1-b]oxazole

Product 1

HCID 167264821-[6-(4-Fluorophenyl)imidazo[2,1-b][1,3]oxazol-5-yl]ethanoneYield 86%

Reagents, catalysts & solvents 1

HCID 1118Sulfuric AcidSolvent

Conditions

Temperature
135 °C

Procedure

To a mixture of 6-(4-fluorophenyl)-imidazo[2,1-b]oxazole (2675 g, 13.23 mol) and acetic anhydride (6.35 l) is added 160 ml of concentrated sulfuric acid. The reaction mixture is heated at 135° C. for 1.5 hours, then cooled to 80° C. with an ice bath. The reaction mixture is slowly quenched with 12.5 l of water. The solids are stirred overnight, filtered and air-dried. The solids are again suspended in water (15 l), stirred overnight, filtered, and washed with water (4 l) and then with toluene (4 l). The solid is dried under vacuum at 60° C., to give 2771 g (86%) of a dark brown solid; M.p.=173° C.; 300 MHz 1H NMR (DMSO-d6) δ 8.25-8.19 (m, 2H), 7.75-7.68 (m, 2H), 7.35-7.25 (m, 2H), 2.15 (s, 3H). LCMS: 245 [M+H].

Workup

  1. temperaturecooled to 80° C. with an ice bath
  2. customThe reaction mixture is slowly quenched with 12.5 l of water
  3. filtrationfiltered
  4. customair-dried
  5. stirringstirred overnight
  6. filtrationfiltered
  7. washwashed with water (4 l)
  8. customThe solid is dried under vacuum at 60° C.

Sources & evidence

ORD record
ord-4318b618e5674f148c29af60b037923d
Source dataset
uspto-grants-2012_05
Patent number
US08178672B2

Reaction notes

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