Trifluoroacetic acid → 1-[Di(methoxycarbonyl)-methyl]-4-nitronaphthalene-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Trifluoroacetic acid (36 mL) was added in one portion to a mixture of 5 (9.20 g, 19.7 mmol) and anisole (12.16 g, 20 mmol), and the resulting solution was stirred at 20° C. for 10 min and then diluted with cold water (800 mL). The precipitated semi-solid was collected, dissolved in EtOAc and the solution was washed with water, dried (Na2SO4) and then concentrated under reduced pressure below 30° C. The residue was triturated with iPr2O to provide a crude product, which was recrystallised from EtOAc/iPr2O/petroleum ether/AcOH (1drop) to give 1-[di(methoxycarbonyl)-methyl]-4-nitronaphthalene-2-carboxylic acid (6) (6.37 g, 93%), mp 153-154° C. (dec.). 1H NMR [(CD3)2SO] δ 14.1 (br s, 1H, CO2H), 8.62 (s, 1H, H-3), 8.36 (d, J=8.2 Hz, 1H, H-5), 8.30 (d, J=8.7 Hz, 1H, H-8), 7.92 (br t, J=7.6 Hz, 1H, H-6), 7.84 (br t, J=7.7 Hz, 1H, H-7), 6.65 (s, 1H, ArCH), 3.63 (s, 6H, 2×CO2CH3). Anal. Calculated for C16H13NO8 : C, 55.3; H, 3.8; N, 4.0. Found: C, 55.4; H, 3.8; N, 3.7%.

Provenance & Evidence