2,4-Dichloropyrrolo[2,1-f][1,2,4]triazine

918538-04-2

918538-05-3

The general procedure for the synthesis of 2,4-dichloropyrrolo[2,1-f][1,2,4]triazines using pyrrolo[2,1-f][1,2,4]triazine-2,4(1H,3H)-dione as a starting material was as follows: to a solvent mixture containing diisopropylethylamine (4.5 mL) and toluene (20 mL) under nitrogen protection, intermediate 5 (1.6 g, 10.4 mmol) and phosphorous trichloride (2.94 mL). The reaction mixture was transferred to a sealed tube and the reaction was heated at 120 °C for 20 hours. After the reaction was completed, the mixture was slowly poured into ice-cooled saturated sodium bicarbonate solution (50 mL) and stirred for 15 minutes. The aqueous phase was extracted with dichloromethane (3 x 50 mL) and the organic layers were combined. The organic layer was washed once with saturated saline (50 mL), dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography with gradient elution of hexane solution with 50-100% dichloromethane as eluent to afford the target product 2,4-dichloropyrrolo[2,1-f][1,2,4]triazine as a light brown solid (1.2 g, 86% yield). The product was characterized by 1H NMR (CDCl3) and mass spectrometry: 1H NMR (CDCl3): δ 6.98 (1H, m), 7.05 (1H, m), 7.86 (1H, m); MS: 187 (M+).