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

HRID 1925207Notes

Reaction equation

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

Participants

Conditions

Temperature: 135 °C

Procedure

To a mixture of 6-(2-chlorophenyl)-imidazo[2,1-b]oxazole (1.0 g, 4.57 mmol) and acetic anhydride (23 ml) is added 3 drops of concentrated sulfuric acid. The reaction mixture is heated at 135° C. for 1 hour. The reaction mixture is then poured onto 50 ml of ice, and diluted with 100 ml of water and the resulting mixture is extracted three times with 75 ml each of ethyl acetate. The combined extracts are dried with magnesium sulfate, filtered and concentrated in vacuo, to give a brown oil. The product is purified by flash chromatography on silica gel (hexane/ethyl acetate 3:1), yielding 994 mg of an off-white solid (83%). M.p.=121-122° C.; 300 MHz 1H NMR (CDCl3) δ: 8.02 (d, J=1.6 Hz, 1H), 7.56-7.38 (m, 5H), 2.05 (s, 3H). LCMS: 261 [M+H]; calc. for C13H9ClN2O2: C, 59.84; H, 3.48; N, 10.74; found. C, 60.18; H, 3.16; N, 10.61.

Workup

extractionthe resulting mixture is extracted three times with 75 ml each of ethyl acetate
dry with materialThe combined extracts are dried with magnesium sulfate
filtrationfiltered
concentrationconcentrated in vacuo
customto give a brown oil
customThe product is purified by flash chromatography on silica gel (hexane/ethyl acetate 3:1)

Sources & evidence

ORD record: ord-7ecaa6005e1641c99d7773d0ea03a517
Source dataset: uspto-grants-2012_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08178672B2

Reaction notes

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