Sodium Carbonate → Sodium 4-methyl-6-(2-methyl-3-(4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxamido)phenyl)-3-oxo-3,4-dihydropyrazin-2-olate

Participants

Reaction Steps

A 250-mL three-neck round-bottomed flask equipped with a mechanical stirrer, reflux condenser and nitrogen inlet was charged with 1,4-dioxane (100 mL) and aqueous 2.0 M sodium carbonate (15 mL, 29.5 mmol). After bubbling nitrogen through the resulting solution for 15 minutes, 5 (8.44 g, 29.5 mmol), 9 (12.9 g, 32.5 mmol) and tetrakis(triphenylphosphine)palladium (2.38 g, 2.06 mmol) were added and the reaction mixture then heated at reflux for 20 h. After this time the reaction was cooled to room temperature and filtered through a pad of Celite 521. The filter cake was washed with a 1:1 solution of methanol/methylene chloride (350 mL) and the filter cake discarded. On standing a precipitate formed in the filtrate and this solid was filtered. The filter cake was triturated with ethyl acetate (50 mL), filtered and dried under vacuum. The resulting solid was suspended in water (75 mL), filtered and the filter cake washed with water (25 mL). The filter cake was dried to a constant weight to give a 53% yield (6.57 g) of 10 as a light yellow solid: mp 225-230° C. dec, 1H NMR (500 MHz, DMSO-d6) δ 9.73 (s, 1H), 7.66 (s, 1H), 7.21 (m, 1H), 7.16 (m, 2H), 6.37 (s, 1H), 2.75 (m, 2H), 2.61 (m, 2H), 2.20 (s, 3H), 1.77 (m, 4H); MS (ESI+) m/z 418 (M+H).

Provenance & Evidence