Potassium Carbonate → HCID 53233006, compound

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A mixture of 4-formyl-3-nitro-benzoic acid methyl ester (14.1 g, 67.5 mmol), mercapto-acetic acid ethyl ester (8.17 mL, 74.2 mmol) and potassium carbonate (12.2 g, 87.7 mmol) in 100 mL of anhydrous DMF was heated at 50 degrees Celsius for about 6 hours. After cooling to rt, the mixture was poured into ice-water and the mixture was stirred for around 40 mins. The solid formed was collected, washed with water and dried to give benzo[b]thiophene-2,6-dicarboxylic acid 2-ethyl ester-6-methyl ester as a pale solid (16.1 g, 90.4%). MS: calc'd 265 (MH+), exp 265 (MH+). 1H NMR (CDCl3, 400 MHz), 8.60 (s, 1H), 8.09 (s, 1H), 8.06 (d, 1H, J=8.8 Hz), 7.93 (d, 1H, J=8.8 Hz), 4.45 (q, 2H, J=6.8 Hz), 4.0 (s, 3H), 1.50 (t, 3H, J=7.2 Hz).

Provenance & Evidence