Showing papers by "Malcolm F. G. Stevens published in 1974"
TL;DR: In this paper, the nucleophilic attack by the amines at C-4 of the triazine ring is implicated in these transformations, leading to the triazenylquinazolines (19) and NNN-trisubstituted 2-aminobenzamidines (4) in excellent yields.
Abstract: 4-Arylamino-1,2,3-benzotriazines (1) decompose in piperidine and related secondary amines to afford NNN′-trisubstituted 2-aminobenzamidines (4) in excellent yields. 4-o-Aminoanilinobenzotriazine (1f) yields 2-(2-aminophenyl)benzimidazole (9) when heated in ethylene glycol or piperidine. Nucleophilic attack by the amines at C-4 of the triazine ring is implicated in these transformations. 1-o-Cyanophenyl-3-m-cyanophenyltriazene (13a) is unreactive in piperidine whereas the p-cyanophenyltriazene isomer (13b) yields 2-amino-N′-p-cyanophenyl-NN-pentamethylenebenzamidine (4b). 1,3-Bis-o-cyanophenyltriazene (13c) rearranges and decomposes in boiling piperidine, pyrrolidine, morpholine, diethylamine, di-n-propylamine, and piperazine to afford the triazenylquinazolines (19)–(24), respectively.
9 citations
TL;DR: The 3-substituted 4-arylimino-3,4-dihydro-4-imino-1,2,3-benzotriazines are stable in acetic acid as discussed by the authors.
Abstract: 3-Substituted 3,4-dihydro-4-imino-1,2,3-benzotriazines (1) rearrange to the isomeric substituted 4-amino-1,2,3-benzotriazines (2) in acetic acid regardless of the nature of the 3-substituent. 3-Substituted 4-arylimino-3,4-dihydro-1,2,3-benzotriazines (4) are stable in acetic acid.
6 citations
TL;DR: The reaction of the bases at the exocyclic imino-substituent is implicated in these isomerisations since the 3-benzyltriazine (1h) and the 3substituted 4-arylimino-3,4-dihydro-1,2,3-benzotriazines (4a-e) are all unreactive as discussed by the authors.
Abstract: 3-Substituted 3,4-dihydro-4-imino-1,2,3-benzotriazines (1a–g) undergo ring opening in piperidine, morpholine, and pyrrolidine to afford the o-cyanophenyltriazenes (2a–g), respectively. Attack by the bases at the exocyclic imino-substituent is implicated in these isomerisations since the 3-benzyltriazine (1h) and the 3-substituted 4-arylimino-3,4-dihydro-1,2,3-benzotriazines (4a–e) are all unreactive. Similarly, reaction of the bases at the exocyclic imino-group of the N-hydroxy-tautomer of 4-aminobenzotriazine 3-oxide (6) leads to o-azidobenzonitrile (8).The fused 1,2,3-benzotriazines (11) and (13) react with secondary amines to afford 3,3-dialkyl- or polymethylenetriazenes, but the reactivity of 3-substituted 1,2,3-benzotriazin-4(3H)-ones (19) towards piperidine and its analogues is dependent on the nature of the 3-substituent.
5 citations
TL;DR: In the presence of βγ-unsaturated esters, 1,2,3-benzotriazin-4(3H)-one (1) is thermally transformed into the quinazolino[3, 2-c][1, 2,3]benzoteitriazinone (2), which then undergoes cleavage of the N(2)-N(3) bond in the triazine ring to afford the quinnazolinylphenylhydrazones (14).
Abstract: In the presence of βγ-unsaturated esters, 1,2,3-benzotriazin-4(3H)-one (1) is thermally transformed into the quinazolino[3,2-c][1,2,3]benzotriazinone (13), which then undergoes cleavage of the N(2)–N(3) bond in the triazine ring to afford the quinazolinylphenylhydrazones (14). The initial step in the reaction probably involves a nucleophilic attack of one molecule of the triazinone (1) at the reactive 4-position of another molecule. 3-Alkyl- and 3-aralkyl-1,2,3-benzotriazin-4(3H)-ones are all stable in boiling ethyl cyanoacetate, but the 3-arylbenzotriazinones undergo thermal heterolysis of the N(2)–N(3) bond, followed by reaction with the ester, to yield phenylcarbamoylphenylhydrazones.
5 citations