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

HRID 609630Notes

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 0.5 M 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 chloromethane, followed by column chromatography on alumina using dichloromethane. (5-Bromobenzofuran-3-yl)acetic acid ethyl ester was obtained as a low melting solid (4.2 g, 57%), mp 38-40° C. 1H NMR 250 MHz, CDCl3) δ1.28 (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-a8b3c882dd0c4dfdb44f895900a1cf83
Source dataset: uspto-grants-1999_12
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05998416

Reaction notes

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