Benzyl Bromide → 4-Methyl-pent-2-enoic acid benzyl ester

HRID 268630Notes

Reaction equation

[CH3:1][CH:2]([CH3:8])[CH:3]=[CH:4][C:5]([OH:7])=[O:6].C([O-])([O-])=O.[K+].[K+].[CH2:15](Br)[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1>CC(C)=O>[CH2:15]([O:6][C:5](=[O:7])[CH:4]=[CH:3][CH:2]([CH3:8])[CH3:1])[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1

Participants

Conditions

Temperature: 25 °C

Procedure

To a solution of 4-methyl-2-pentenoic acid (24.0 g, 210 mmol; commercially available from TCI America) in acetone (300 mL) was added K2CO3 (55.8 g, 404 mmol) and the reaction was stirred at 25° C. for 30 min. A solution of benzyl bromide (25.2 mL, 212 mmol; commercially available from Sigma Aldrich) in acetone (100 mL) was then added drop-wise. The reaction mixture was subsequently heated to reflux for 16 hrs. After cooling to 25° C., the acetone was removed under reduced pressure and ether (300 mL) and water (300 mL) were added and the organic layer was separated, washed with brine and dried over Na2SO4. After concentration, the crude product was subjected to silica gel chromatography (1-5% Ether/Hex) to afford 4-methyl-pent-2-enoic acid benzyl ester (40.5 g, 98%): H-NMR (CDCI3) δ 7.36-7.28 (m, 5 H), 6.96 (dd, 1 H), 5.79 (d, 1 H), 5.14 (s, 2 H), 2.45-2.40 (m, 1 H), 1.01 (d, 6 H).

Workup

temperatureThe reaction mixture was subsequently heated
temperatureto reflux for 16 hrs
temperatureAfter cooling to 25° C.
customthe acetone was removed under reduced pressure and ether (300 mL) and water (300 mL)
additionwere added
customthe organic layer was separated
washwashed with brine
dry with materialdried over Na2SO4
concentrationAfter concentration

Sources & evidence

ORD record: ord-3e5800d55a164ddb97f03cc24ba1e68f
Source dataset: uspto-grants-2008_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07446121B2

Reaction notes

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