254-87-5Relevant articles and documents
3-Substituted Benzo[ e][1,2,4]triazines: Synthesis and Electronic Effects of the C(3) Substituent
Bodzioch, Agnieszka,Pomik?o, Dominika,Celeda, Ma?gorzata,Pietrzak, Anna,Kaszyński, Piotr
, p. 6377 - 6394 (2019/05/24)
A series of 19 structurally diverse C(3)-substituted derivatives of benzo[e][1,2,4]triazine were synthesized from 3-chloro- (1c) and 3-iodobenzo[e][1,2,4]triazine (1d) obtained in three steps from 2-nitroaniline in 37-55% yields. Nucleophilic aromatic substitution and metal-catalyzed (Pd, Cu) reactions led to functional derivatives that include alkyl (C5H11), (het)aryl (Ph, 2-thienyl, ferrocenyl), ArCC, amine (NHPh and morpholine), PO(OEt)2, sulfanyl (SBu-t), alkoxide (OEt, OMe), and CN. The synthesis of C(3)-CF3 derivative 1g via the Ruppert reaction with 1d and its 1-oxide analogue 2d led to the substitution followed by formal addition of HCF3 to the C?N bond. Pd-catalyzed carbonylation reactions of 1d and 2d did not give the corresponding C(3)-carboxylic acids. Therefore, acid 1f was obtained through hydrolysis of the CN. The substituent effect on the electronic structure of the benzo[e][1,2,4]triazine ring was investigated by spectroscopic methods (UV-vis and NMR) augmented with density functional theory calculations. Results show significant effect of the C(3) substituent on the (1) transition energy and good correlation of the 1H NMR chemical shift with the substituent constant σp. Molecular and crystal structures of six derivatives were established with the single-crystal X-ray diffraction method, and the substituent impact on the molecular geometry was investigated.
Complete 1H, 13C and 15N NMR assignment of tirapazamine and related 1,2,4-benzotriazine N-oxides
Boyd, Maruta,Hay, Michael P.,Boyd, Peter D. W.
, p. 948 - 954 (2008/02/03)
1H, 13C and 15N NMR measurements (1D and 2D including 1H-15N gs-HMBC) have been carried out on 3-amino-1, 2,4-benzotriazine and a series of N-oxides and complete assignments established. N-Oxidation at any position resulted in large upfield shifts of the corresponding N-1 and N-2 resonances and downfield shifts for N-4 with the exception of the 3-amino-1,2,4-benzotriazine 1-oxide in which a small upfield shift of N-4 was observed. Density functional GIAO calculations of the 15N and 13C chemical shifts [B3LYP/6-31G(d)//B3LYP/6- 311+G(2d,p)] gave good agreement with experimental values confirming the assignments. The combination of 13C and 15N NMR provides an unambiguous method for assigning the 1H and 13C resonances of N-oxides of 1,2,4-benzotriazines. Copyright
Electrochemical reduction of o-nitrophenylhydrazides into 1,2,4-benzotriazines.
Chibani, A.,Hazard, R.,Tallec, A.
, p. 343 - 352 (2007/10/02)
Phenylhydroxylamines, obtained in aqueous medium, by electroreduction of o-nitrophenylhydrazides (o-NO2-C6H4-NH-NHCOR), undergo a disproportionation reaction leading finally to the corresponding o-amino compound; the latter partially rearranges into an o-amidophenylhydrazine (o-RCONH-C6H4-NH-NH2).In a basic media, the disproportionation reaction is concurrent with a ring closure of the intermediate hydroxylamine giving rise to a 1,2,4-benzotriazine.The latter is also obtained by anodic oxidation of the amine, mixed with anilide resulting from the hydrazine oxidation.Electroreduction, immediately followed by an anodic oxidation gives rise to about 50percent yield in the expected triazine.In an acidic media, disproportionation is faster, but the resulting amine undergoes a ring closure reaction into dihydrobenzotriazine when R = H or CH3.Subsequent oxidation of the latter gives rise to 75percent yield of the triazine, mixed with N-aminobenzimidazole resulting from the hydrazine.When R = Ph, the amine is stable but only very poor yields of triazine are obtained by anodic oxidation; the major evolution is probably the formation of an unstable benzoylbenzotriazole.Key words: cyclic voltammetry, controlled potential reduction and oxidation, 1,2,4-benzotriazine, 1-amino-2-alkylbenzimidazoles, organic electrosynthesis.
