Transformation of Nitrogen Substituents

6-dimethyl-l,2,3-triazine 2-imine 18d was protonated using cone. HBr in Et20 to afford 2-amino-4,6-dimethyl-1,2,3-triazinium bromide in 83% yield, or further transformed with nitrous acid into 4,6-dimethyl-l,2,3-triazine, respectively 1988YZ1056 . 

The imine function in the 2-imines 18d-f is acylated readily with acetyl or benzoyl chloride to generate the A -acyl species 235a-d (Equation 97) however, treatment of 18d with acetic anhydride in the presence of potassium carbonate affords the 2-(l,2,3-triazin-5-yl)imine 236 (Equation 98) 1988YZ1056 . 

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