Reaction Steps
A solution of 2,4-dichloro-6-methoxy-1,3,5-triazine (9.00 g, 50.0 mmol) in 100 mL of acetone was cooled to 0° C. and, under stirring, solid 4-amino phenol (5.46 g, 50.0 mmol) was added in small portion, over ca 2 min. The white suspension was then let to warm to room temperature and stirred for further 1 h, while being neutralized with a 2 M aqueous solution of Na2CO3 during the reaction. The mixture was then poured into 500 mL of ice/water and the resulting white precipitate was filtered and dried, to give 9.6 g (38.0 mmol, yield 76%) of 4-[(4-chloro-6-methoxy-1,3,5-triazin-2-yl)amino]phenol that can be used without further purifications. An analytical sample can be obtained by flash chromatography (CC, SiO2, petroleum ether/Et2O 1:1, Rf=: 0.14). The NMR analysis (DMSO d6) reveals the presence, in solution, of 2 rotational isomers (molar ratio 7:3). M.p was 172° C. IR ν(NH) 3476 cm−1. ν(OH) 3269 cm−1. Major isomer: 1H NMR (DMSO d6) δ=3.94 (s, 3H, OCH3); 6.79 (d, J=8.8 Hz, 2H, CH Ar), 7.48 (d, J=8.8 Hz, 2H, CH Ar), 9.40 (s, 1H, OH), 10.46 (s, 1H, NH). 13C NMR (DMSO d6) δ 55.52 (1C, OCH3); 115.46 (2C, CH Ar), 123.91 (2C, CH Ar), 129.49 (1C, C Ar), 154.44 (1C, C Ar), 164.81 (1C, C Ar), 169.57 (1C, C Ar), 171.23 (1C, C Ar). Minor isomer: 1H NMR (DMSO d6) δ 3.96 (s, 3H, OCH3); 6.79 (d, J=8.9 Hz, 2H, CH Ar), 7.39 (d, J=8.9 Hz, 2H, CH Ar), 9.42 (bs, 1H, OH), 10.10.32 (s, 1H, NH). 13C NMR (DMSO d6) δ=55.10 (1C, OCH3); 115.46 (2C, CH Ar), 123.03 (2C, CH Ar), 129.26 (1C, C Ar), 154.76 (1C, C Ar), 165.20 (1C, C Ar), 170.48 (1C, C Ar), 170.64 (1C, C Ar).
