Dimethyl malonate → 1,3-Dimethyl 2-(4-bromo-2-nitrophenyl)propanedioate

Participants

Reaction Conditions

Reaction Steps

Sodium hydride (60% oil dispersion, 4.00 g, 100 mmol) was added to a dry 500 ml flask under nitrogen and washed with three 25 ml portions of hexanes. Anhydrous DMSO (100 ml) was added, followed by dimethyl malonate (11.4 ml, 100 mmol). The reaction was heated briefly to 100° C. with stirring, then cooled to room temperature. 2,5-Dibromonitrobenzene (12.9 g, 46.0 mmol) was added and the reaction was heated at 110° C. for 2 hrs. After cooling to room temperature, the solution was added in portions to 300 ml of saturated aqueous ammonium chloride with 150 ml of 1:1 hexanes/ethyl acetate. The organic layer was washed with 300 ml of saturated aqueous ammonium chloride, four 200 ml portions of water, and 200 ml of saturated aqueous sodium chloride. The organic layer was dried over magnesium sulfate and the solvent was evaporated to give 13.6 g of crude dimethyl 2-(4-bromo-2-nitrophenyl)malonate as a brown oil. This material (30-40 mmol) was heated to 110° C. in 250 ml DMSO with 3.6 g (84 mmol) of lithium chloride and 750 mg (42 mmol) of water for 4.5 hrs. The reaction was cooled to room temperature and added to 300 ml of ethyl acetate with 300 ml of saturated aqueous sodium chloride. The organic layer was washed with a second portion of 300 ml saturated aqueous sodium chloride, dried over magnesium sulfate, and the solvent was removed to give 11.1 g brown oil. This material was adsorbed on 40 g of silica gel and applied to a column containing another 80 g of silica gel. Elution with 0-10% ethyl acetate in hexanes gave 3.53 g (28% from 2,5-dibromonitrobenzene) of methyl (4-bromo-2-nitrophenyl) acetate as a yellow solid.

Provenance & Evidence