Pyrrolo[1,2-f][1,2,4]triazin-4-amine

937046-97-4

3473-63-0

159326-68-8

To a stirred suspension of 1-amino-1H-pyrrole-2-carbonitrile hydrochloride (50 g, 0.35 mol) in anhydrous ethanol (800 mL) was sequentially added formamidine acetate (181.3 g, 1.74 mol) and potassium phosphate (370 g, 1.74 mol). The reaction mixture was heated to 78 °C under nitrogen protection and maintained for 18 hours. After completion of the reaction, it was cooled to room temperature, the reaction mixture was filtered and the filtrate was concentrated to dryness under vacuum. The residue was mixed with ice water (2 L) and the resulting dark gray-brown solid was collected by filtration. The filter cake was washed with water, blotted dry, the solid was dissolved in hot ethyl acetate and filtered over a funnel into a collection vessel. The resulting dark solution was filtered through a 30/40 Magnesol long stopper, and the light yellow filtrate was collected and concentrated to dryness under vacuum to give a yellow solid product (20.6 g, 44.1% yield). The Magnesol plug was washed with ethyl acetate/ethanol and the washings were concentrated under vacuum to give additional product (10.7 g, 23%). The aqueous phase filtrate was extracted with ethyl acetate and the organic phase was dried, Magnesol filtered and concentrated to give a further purified product (6.3 g, 14%), bringing the total yield to 37.6 g (81%). The product was characterized by 1H-NMR (CD3OD) and LC/MS (+ESI): 1H-NMR δ 7.72 (s, 1H), 7.52 (dd, 1H, J = 2.5, 1.6 Hz), 6.85 (dd, 1H, J = 4.5, 1.6 Hz), 6.64 (dd, 1H, J = 4.5, 2.7 Hz); LC/MS m/z = 135.1 [M + H].