Ethyl Acetate → Ethyl 2-(5-bromobenzofuran-3-yl)acetate

HRID 365418Notes

Reaction equation

C[Si]([N-][Si](C)(C)C)(C)C.[K+].[Br:11][C:12]1[CH:13]=[CH:14][C:15]2[O:19][CH2:18][C:17](=O)[C:16]=2[CH:21]=1.[Cl-].[NH4+].[C:24]([O:27][CH2:28][CH3:29])(=[O:26])[CH3:25]>O1CCCC1.C1(C)C=CC=CC=1>[CH2:28]([O:27][C:24](=[O:26])[CH2:25][C:17]1[C:16]2[CH:21]=[C:12]([Br:11])[CH:13]=[CH:14][C:15]=2[O:19][CH:18]=1)[CH3:29]

Participants

Conditions

Temperature: -78 °C

Procedure

To a solution of triethyl phosphonoacetate (6 ml, 30.2 mmol) in dry tetrahydrofuran (200 ml) at -78° C. was added a solution of potassium bis(trimethylsilyl)amide in toluene (58 ml of a 0.5M solution). After stirring for 2 hours at -78° C., 5-bromobenzofuran-3-one (5.5 g, 26 mmol) was added dropwise. The resulting solution was stirred 1 hour at -78° C. and overnight at room temperature. Saturated aqueous ammonium chloride solution and ethyl acetate were added. The organic layer was separated and evaporated to dryness to give the crude title compound which was purified by column chromatography on silica using dichloromethane, followed by column chromatography on alumina using dichloromethane. 5-Bromobenzofuran-3-ylacetic acid ethyl ester was obtained as a low melting solid (4.2 g, 57%). mp 38-40° C. 1H NMR (250 MHz, CDCl3) δ 1.28 (3H, t, J=7 Hz), 3.65 (2H, d, J=1 Hz), 4.20 (2H, q, J=7 Hz), 7.36 (1H, s), 7.38 (1H, d, J=2 Hz), 7.63 (1H, s), 7.71 (1H, d, J=2 Hz).

Workup

stirringThe resulting solution was stirred 1 hour at -78° C. and overnight at room temperature
customThe organic layer was separated
customevaporated to dryness
customto give the crude title compound which
customwas purified by column chromatography on silica

Sources & evidence

ORD record: ord-3abbf594f4dd47ce87419436cf65cc06
Source dataset: uspto-grants-2000_10
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06127388

Reaction notes

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