Rings Containing Three Heteroatoms The Triazines

Pyrimidines have been extensively smdied as a source for antibacterial and antiparasitic agents that act as folate reductase inhibitors (see, for example, pyrimethamine [38-5]). This activity is maintained in compounds that incorporate an additional ring of nitrogen. A partly reduced 1,3,5 triazine, cycloguanil (89-4), shows 

Preparation of the anticonvulsant agent lamotigrine (91-3) illustrates an alternate approach to 1,2,4-triazines. Condensation of acyl cyanide (91-1) with dicyanamide gives imine (91-2) as the initial product. Treatment of that intermediate with a base leads to the addition of the guanidino anion to the nitrile and thus the formation of the triazine ring [92]. 

Tagmann, E. Sury, E. Hoffmann, K. Helv. Chim. Acta 1952, 35, 1541. 

Morrison, H. G. Jones, P. Summa, V. 2007, European Patent EP1919700. 

Ishizumi, K. Kojima, A. Antoku, R Chem. Pharm. Bull. 1991, 39, 2288. 

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