Pyrimidine 37 (Example 20, 4.72 g, 13.7 mmol) is dissolved in 60 mL acetic acid (30%) and heated to 70° C. NaNO2 (1.4 g, 20.03 mmol) dissolved in 5 mL water is added drop wise until KJ-starch paper remains black. After cooling to 0° C. in an ice-bath, the purple precipitate is collected by filtration and recrystallized from acetone to yield 3.9 g (10.54 mmol, 77%) of a purple solid. 1H-NMR (400 MHz, DMSO-d6) δ=10.03 (d, J=4.0, 1H, 5-NHa), 10.00 (t, J=5.8, 1H, CF3CONH), 8.01 (d, J=4.0, 1H, 5-NHb), 7.86 (s, 1H, 1-NHa), 7.81 (s, 1H, 1-NHb), 7.51 (d, J=8.1, 2H, ArH), 7.30 (d, J=8.1, 2H, ArH), 5.54 (s, 2H, OCH2), 4.38 (d, J=5.8, 2H, CH2N) ppm.
