Trifluoroacetic acid → N4-(3,4-dibromophenyl)pyrido[3,4-d]pyrimidine-4,6-diamine

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Reaction Steps

To a stirred heterogeneous mixture of compound 216 (4.08 g, 7.92 mmol) and DCM (80 mL) was added trifluoroacetic acid (6.07 mL, 79.2 mmol), followed by anisole (1.73 mL, 15.8 mmol), and the mixture was stirred further at room temperature for 46 h. It was poured into petroleum ether (500 mL) and stirred at room temperature for ca. 15 min. Petroleum ether layer was decanted and discarded. The process was repeated with more petroleum ether (400 mL). The solid left behind was dissolved in minimum MeOH (120 mL) and 5M NH3 (150 mL) was added at 0° C. and stirred at room temperature for 15 min. The solid was collected and washed successively with water (5×20 mL), petroleum ether-ethyl acetate=5:1 (5×20 mL), and dried to give N4-(3,4-dibromophenyl)pyrido[3,4-d]pyrimidine-4,6-diamine (225) (2.47 g, 79%), mp 265-268° C.; 1H NMR δ [(CD3)2SO] 9.80 (s, 1H), 8.72 (s, 1H), 8.44 (d, J=2.2 Hz, 1H), 8.42 (s, 1H), 7.90 (dd, J=8.8, 2.2 Hz, 1H), 7.74 (d, J=8.8 Hz, 1H), 7.14 (s, 1H), 6.30 (s, 2H). Anal. Calcd for C13H9Br2N5.0.1hexane: C, 40.47; H, 2.60; N, 17.35. Found C, 40.16; H, 2.45; N, 17.20.

Provenance & Evidence