Diethyl Oxalate → Ethyl 4-oxo-1,4-dihydrothieno[3,2-d]pyrimidine-2-carboxylate

Participants

Reaction Steps

A mixture of 3-aminothiophene-2-carboxamide (1.23 g, 8.65 mmol) and EtOH (25 mL) was treated with NaOEt (1.2 g, 17.3 mmol) and diethyloxalate (2.3 mL, 17.3 mmol), refluxed for 18 h, cooled, concentrated in vacuo, treated with water, acidified with HOAc and filtered to give the title compound (1.43 g, 74%) as a cream solid: IR νmax Nujol)/cm−1 3180, 3119, 3078, 3006, 2955, 2924, 2854, 1737, 1667, 1651, 1300 and 1176; NMR δH (400 MHz, DMSO) 1.37 (3H, t, J 7.0 Hz), 4.40 (2H, q, J 7.0 Hz), 7.58 (1H, d, J 5.0 Hz), 8.30 (1H, d, J 5.1 Hz), and 12.92 (1H, s).

Provenance & Evidence