Acetone → 2-Bromo-1-thiophen-3-yl-butan-1-one

HRID 81841Notes

Reaction equation

CC[Mg+].[Br-].C[C:6]([OH:9])(C)C.[CH3:10][C:11]([CH3:13])=[O:12].[Br:14][CH:15]([CH2:23][CH3:24])[C:16]([C:18]1[CH:22]=[CH:21][S:20][CH:19]=1)=[O:17]>C1C=CC=CC=1>[Br:14][CH:15]([CH2:23][CH3:24])[C:16]([C:18]1[CH:22]=[CH:21][S:20][CH:19]=1)=[O:17].[S:20]1[CH:21]=[CH:22][C:18]([CH:16]([CH2:15][CH3:23])[C:6](=[O:9])[CH2:10][C:11](=[O:12])[CH3:13])=[CH:19]1

Participants

Conditions

Temperature: 0 °C

Procedure

EtMgBr (6.69 ml, 13 mmol, 2 M in ethyl ether) in benzene (10 ml) was cooled to zero degrees C., and tBuOH (1.28 ml, 13 mmol) was slowly added. The reaction mixture was stirred at zero degrees C. for 5 minutes, then acetone (530 ul, 7 mmol) was added, followed by a solution of 2-Bromo-1-thiophen-3-yl-butan-1-one (1.3 g, 6 mmol) in 3 ml benzene via cannula. The reaction mixture was heated to reflux for 1 hour, and acetone (250 ul) was added. The reaction mixture was heated 2 hours more at reflux. The reaction was cooled, quenched with 1 N HCl (10 ml), extracted three times with diethyl ether, washed brine, and dried over magnesium sulfate. The solvent was removed in vacuo and the residue chromatographed (5% ethyl acetate/hexanes) to give 247 mg of 2-Bromo-1-thiophen-3-yl-butan-1-one starting material and 520 mg of 5-Thiophen-3-yl-heptane-2,4-dione, 44%.

Workup

temperatureThe reaction mixture was heated
temperatureto reflux for 1 hour
temperatureThe reaction mixture was heated 2 hours more
temperatureat reflux
temperatureThe reaction was cooled
customquenched with 1 N HCl (10 ml)
extractionextracted three times with diethyl ether
washwashed brine
dry with materialdried over magnesium sulfate
customThe solvent was removed in vacuo
customthe residue chromatographed (5% ethyl acetate/hexanes)

Sources & evidence

ORD record: ord-33848afc06574e7288b8338ac9572e89
Source dataset: uspto-grants-2014_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08846705B2

Reaction notes

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