Bromoform → 39647-01-3

Participants

Reaction Steps

To a stirred solution of methyl methacrylate (3.15 g, 31.5 mmol.) and benzyltriethylammonium chloride (0.72 g, 3.2 mmol.) in aqueous NaOH (12.6 ml of a 50% w/w solution, 0.16 mol.) was slowly added bromoform (15.95 g, 63 mmol.) and the deep brown solution stirred at room temperature for 18 hours. The mixture was partitioned between dichloromethane (50 ml) and water (50 ml), the layers separated and the aqueous layer extracted with further dichloromethane (50 ml). The organic layers were combined, washed with brine, dried (MgSO4) and evaporated to give the desired methyl 2,2-dibromo-1-methylcyclopropanecarboxylate (8.0 g, 93%). This was dissolved in a mixture of TBF (70 ml) and water (30 ml) and LiOH (1.05 g, 44 mmol.) added. The mixture was vigorously stirred at room temperature for 20 hours then the THF was evaporated and the aqueous residue washed with ether (2×25 ml), acidified with 5N HCl to pH1 and extracted with ethyl acetate (2×50 ml). The combined ethyl acetate layers were dried (MgSO4) and evaporated to give the desired 2,2-dibromo-1-methylcyclopropanecarboxylic acid as a tan solid (4.2 g, 55%) which was dissolved in 2,2,2-trifluoroethanol (200 ml). Silver trifluoroacetate (5.75 g, 26 mmol.) was added under nitrogen and the reaction refluxed in the dark for 16 hours after which time the mixture was filtered and evaporated. The residue was taken up in ether (100 ml), washed with water (100 ml), and with saturated aqueous NaHCO3 (100 ml), then dried (MgSO4) and evaporated to give an oil (1.1 g) which was purified by chromatography (SiO2; dichloromethane:hexane; 4:1 w/w) to afford the desired 4-bromo-3-methyl-2(5H)-furanone (520 mg).

Provenance & Evidence