Benzyl Bromide → 3-Benzyloxy-2-methyl-4-pyrone

HRID 336123Notes

Reaction equation

[CH3:1][C:2]1[O:8][CH:7]=[CH:6][C:4](=[O:5])[C:3]=1[OH:9].[CH2:10](Br)[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1.C(=O)([O-])[O-].[K+].[K+]>CN(C=O)C>[CH2:10]([O:9][C:3]1[C:4](=[O:5])[CH:6]=[CH:7][O:8][C:2]=1[CH3:1])[C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1

Participants

Conditions

Temperature: 80 °C

Procedure

To a 500 mL flask with 10.0 g (0.08 mol) of maltol (3-hydroxy-2-methyl-4H-pyran-4-one) in 120 mL of anhydrous DMF was added 14.1 mL (0.12 mol) of benzyl bromide and potassium carbonate (16.4 g, 0.12 mol) and heated at 80° C. overnight. After cooling to room temperature, the reaction was filtered and the solvents evaporated. The residual oil was brought up in 100 mL CH2Cl2 and washed twice with a saturated NaHCO3 solution, water, and brine. The organic layer was dried over MgSO4, filtered and concentrated. Product was purified on a silica gel column eluting with 0.5% MeOH in CH2Cl2 to yield a pale yellow solid in 75% yield (12.8 g, 59 mmol). 1H NMR (400 MHz, CDCl3) δ=7.59 (d, J=5.6 Hz, 1H), 7.36 (m, 5H), 6.36 (d, J=5.6 Hz, 1H), 5.15 (s, 2H, OCH2), 2.08 (s, 3H, CH3). ESI-MS(+): m/z 217.03 [M+H]+, 239.07 [M+Na]+.

Workup

temperatureAfter cooling to room temperature
filtrationthe reaction was filtered
customthe solvents evaporated
washwashed twice with a saturated NaHCO3 solution, water, and brine
dry with materialThe organic layer was dried over MgSO4
filtrationfiltered
concentrationconcentrated
customProduct was purified on a silica gel column
washeluting with 0.5% MeOH in CH2Cl2
customto yield a pale yellow solid in 75% yield (12.8 g, 59 mmol)

Sources & evidence

ORD record: ord-b27f57b527d6455c8e38226e6792a10c
Source dataset: uspto-grants-2014_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08889638B2

Reaction notes

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