Reactions of Amino and Imino Groups

In addition to the cases of displacement of 5-amino functions in 2-EWG-substituted l,2,3-ttiazin-2-ium salts yielding 2-EWG-substituted 2,5-dihydro-l,2,3-ttiazin-5-ones (EWG = COOMe, 2,3-(dialkylamino)cyclopropenylium, picryl) 1979CB1535, 1984CHEC(3)369 , examples of hydrolysis of 4,6-disubstituted-5-dialkylamino-2-methyl-l,2,3-triazinium salts 89a and 89d-g generating 2-methyl-2,5-dihydro-l,2,3-triazin-5-ones 22c-g have been reported (Equation 79) 1985BCJ1073 (A), 2002HC0325 (B), 2003H(59)477 (C)). 

The NH proton of 3-aryl-3,4-dihydro-l,2,3-benzotriazin-4-imines is sufficiently acidic to be abstracted by base leading to opening of the triazine ring 1984CHEC(3)369 . A further example for this reactivity is the transformation of 54 (R = Ar) to the triazenes 209 in good yield (Equation 80) 1974J(P1)611 , but compare with Equations 

Attempted preparation of the parent 1,2,3-benzotriazine 2 from 4-hydrazino-l,2,3-benzotriazine (36 = NHNH2) by dehydrogenation and N2 release instead gave the hydrazone 211 together with a small amount of benzonitrile 1975J(P1)31 . Treatment of 4-hydrazino-l,2,3-benzotriazine with pentyl nitrite afforded 4-azido- 

3- benzotriazine 212, while (deviating from the statement made in 1984CHEC(3)369 ) reaction with sodium nitrite in AcOH followed by trapping with resorcinol gave the 2-(tetrazol-5-yl)azobenzene 213 1971JHC785 . 

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Reaction of amino and imino groups with nucleophiles... 

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