Thiophene-3,4-diamine → 2-butyl-1H-thieno[3,4-d]imidazole

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Reaction Steps

A mixture of 3,4-diaminothiophene (1.7 g) and ethyl valeroimidate hydrochloride (3.0 g) in ethanol (30 ml) was stirred at room temperatures for 1.5 hour. 10 The reaction mixture was concentrated and the residue was dissolved in a mixture of ethyl acetate and a saturated aqueous solution of sodium hydrogencarbonate. The organic layer was washed with water, dried and concentrated to dryness. The concentrate was purified by silica gel column chromatography to give crystals. Recrystallization from isopropyl ether afforded colorless crystals (0.72 g, 27%), m.p. 118°-120° C. 1H-NMR(200 MHz, CDCl3)δ: 0.95(3H,t), 1.35-1.54(2H,m), 1.73-1.88(2H,m), 2.79(2H,t), 6.75(2H,br s), 8.50(1H,br s). IR(KBr)cm-1 :3200-2200, 1530, 1480, 1440, 1390, 1240, 1230, 1160, 830, 815, 760, 740.

Provenance & Evidence