Dimethylamine → methyl 6-[(dimethylamino)methyl]-4H-thieno[3,2-b]pyrrole-5-carboxylate

Participants

Reaction Steps

Under N2, to 9 mL of glacial acetic acid were added N,N-dimethylamine (40% aqueous solution) (437 mg, 9.94 mmol), formaldehyde (37% aqueous solution) (283 mg, 9.90 mmol), and methyl 4H-thieno[3,2-b]pyrrole-5-carboxylate (1.8 g, 9.94 mmol). The temperature was kept between 0-5° C. while the components were added. The reaction mixture was heated at reflux for 1 h, and then allowed to stand at rt for 12 h. The mixture was poured onto 30 g of ice, and was brought to pH 10 by careful addition of 10% sodium hydroxide. The temperature was not allowed to exceed 10° C. while the base was added. The gummy substance that precipitated solidified when stored in the refrigerator overnight. The solid was collected and dried in a vacuum. It was recrystallized from petroleum ether (30-60° C.) to yield methyl 6-[(dimethylamino)methyl]-4H-thieno[3,2-b]pyrrole-5-carboxylate (1.65 g, 70%). 1H NMR (400 MHz, CDCl3) δ ppm 2.36 (s, 6H) 3.86 (s, 3H) 3.89 (s, 2H) 6.85 (d, J=5.32 Hz, 1H) 7.28 (d, J=5.32 Hz, 1H) 9.84 (s, 1H).

Provenance & Evidence