3,3’-Bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine and 6,6’-dibromo-3,3’-bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine

Continuing our study on the application of 1,2,4-triazines in organic synthesis [1] we prepared the title compounds as valuable intermediates for metalation reactions leading to functionalized 5,5’-bi-1,2,4-triazines [2].

The mixture of 3,3’-bis(methylsulfanyl)-5,5’-bi-1,2,4-triazine (1) [3] (756 mg, 3.0 mmol) and dimethylamine, 40 wt. % solution in water (40 g), was stirred at room temperature for 20 hrs, and then was heated at 70 °C during a period of 30 min. The precipitate was filtered off and it was purified by column chromatography on silica gel (Merck type 60, 230-400 mesh) using a mixture of chloroform/acetone (100:1) as eluent to give 709 mg (96 %) of 3,3’-bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine of (2) as a yellow solid.

To a solution 2 (246 mg, 1.0 mmol) in acetic acid (8 mL) the bromine (1.6 g, 10 mmol) was added. The reaction mixture was refluxed for 2 hrs. After that time the reaction mixture was cooled to 20 °C, diluted with water (50 mL) and extracted with chloroform (5 x 25 mL). The organic extract was washed with water (125 mL) and dried over MgSO₄. Removal of the solvent in vacuum and purification of the residue by column chromatography on silica gel (Merck type 60, 230-400 mesh) using a mixture of chloroform/acetone (100:1) as eluent gave 222 mg (55 %) of 6,6’-dibromo-3,3’-bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine (3) as a yellow solid.

3,3’-Bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine (2)

M.p. 223-224 °C

¹H NMR (CDCl₃, 200 MHz): 3.37 (s, 12H, 4 x CH₃), 9.44 (s, 2H, H –triazine).

Anal Calcd. for C₁₀H₁₄N₈: C, 48.78; H, 5.69; N, 45.53. Found: C, 48.88; H, 5.57; N, 45.40

6,6’-Dibromo-3,3’-bis(N,N-dimethylamino)-5,5’-bi-1,2,4-triazine (3)

M.p. 122-123 °C

¹H NMR(CCl₄, 60 MHz): 3.85 (s, 12H, 4 x CH₃).

Anal Calcd. for C₁₀H₁₂N₈Br₂: C, 29.73; H, 2.99; N, 27.73. Found: C, 29.84; H, 2.83; N, 27.63