Pyridine → 1-(2,3-Dihydro-1-benzofuran-5-yl)ethanone oxime

HRID 1669142Notes

Reaction equation

HRID 1669142 reaction equation
[NH2:1][OH:2].Cl.[O:4]1[C:8]2[CH:9]=[CH:10][C:11]([C:13](=O)[CH3:14])=[CH:12][C:7]=2[CH2:6][CH2:5]1.N1C=CC=CC=1>CO>[O:4]1[C:8]2[CH:9]=[CH:10][C:11]([C:13](=[N:1][OH:2])[CH3:14])=[CH:12][C:7]=2[CH2:6][CH2:5]1

Participants

5

Reactant 3

HCID 1049PyridineHCID 1452201-(2,3-Dihydro-5-benzofuranyl)ethanoneHCID 443297Hydroxyamine hydrochloride

Product 1

HCID 28214741-(2,3-Dihydro-1-benzofuran-5-yl)ethanone oximeYield 99%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Conditions

Temperature
20 °C

Procedure

NH2OH.HCl (7.3 g, 105 mmol) was added to a stirred solution of ketone 191 (14.2 g, 87.7 mmol) and pyridine (9.2 mL, 114 mmol) in MeOH (100 mL) and the mixture stirred at 20° C. for 16 h. The solvent was evaporated and the residue partitioned between brine and EtOAc. The organic fraction was dried and the solvent evaporated to give crude 1-(2,3-dihydro-1-benzofuran-5-yl)ethanone oxime (15.3 g, 99%). HCl gas was bubbled through a solution of the oxime (15.3 g, 86.5 mmol) in Ac2O (16.3 mL, 173 mmol) and HOAc (54 mL, 865 mmol), and the solution stood at 20° C. for 24 h. The precipitate was poured into ice/water, stirred for 2 h, the solid filtered and washed with water and dried. The aqueous fraction was extracted with DCM (2×50 mL), the combined organic extract dried and the solvent evaporated. The slurry was treated with water (20 mL) and evaporated several times to remove Ac2O. The combined solids were purified by chromatography, eluting with a gradient (50-100%) of EtOAc/pet. ether, to give acetamide 192 (7.94 g, 52%) as a white solid: mp 92-93° C. [lit. (Blade-Font, A.; de Mas Rocabayera, T. J. Chem. Soc. P1, 1982, 814848) mp 93° C.]; 1H NMR δ 7.47 (br s, 1H, H-4), 7.21 (br s, 1H, NH), 6.99 (dd, J=8.5, 2.1 Hz, 1H, H-6), 6.69 (d, J=8.5 Hz, 1H, H-7), 4.55 (t, J=8.7 Hz, 2H, H-2), 3.18 (br t, J=8.7 Hz, 2H, H-3), 2.13 (s, 3H, CH3).

Workup

  1. customThe solvent was evaporated
  2. customthe residue partitioned between brine and EtOAc
  3. customThe organic fraction was dried
  4. customthe solvent evaporated

Sources & evidence

ORD record
ord-f2accae391ad4c1cb18b30eaf5dbcbdf
Source dataset
uspto-grants-2011_08
Patent number
US07989451B2

Reaction notes

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