1.2.3- Benzotriazines synthesis

Pyrrolo[2,1 -c][l, 4]benzodiazepines synthesis, 7, 614 Pyrrolo[l, 6]benzodiazocines synthesis, 7, 515 Pyrrolo[3,4-c]benzopyrazoles reactions, 6, 1034 Pyrrolobenzothiazoles synthesis, 4, 785 Pyrrolo[l, 2-c]benzotriazines synthesis, 4, 240 Pyrrolo[3,4-c]cinnolines synthesis, 4, 240... 

The six-atom cyclization is commonly encountered in 1,2,4-benzotriazine synthesis. In most cases the reactions are real [6 + 0] atom fragment methods since, although reactive intermediates may be involved, the precursors usually have all six atoms present in the molecule. As with the monocyclic compounds, it is usually a C—N bond which is formed in the cyclization but some syntheses take place with N—N bond formation. 

A very commonly used method of 1,2,4-benzotriazine synthesis is the cyclization of formazans (725) by treatment with sulfuric acid in acetic acid. When mixed formazans are... 

BAMBERGER Benzotriazine Synthesis From pyiuvic acid hydrazone 2 and aryldiazoamine salts 1... 

BAMBERGER Benzotriazine Synthesis From pyruvic acid hydrazone 2 and aryidiazoamine salts 1. 

There is only one reported synthesis of a bcnzannulated 1,2,4-triazocine system. 2-Phenylbenz-azete (1), which can be generated from 4-phenyl-l,2,3-benzotriazine by pyrolysis, is reacted with tetrazine 2 to give a [4 + 2] adduct, which loses nitrogen and finally results in the eight-membered-ring derivative after valence isomerization.2... 

The general procedure used for the synthesis of [l,2,3]triazolo[l,2-tf][l,2,4]benzotriazin-l-5(6//)-dione derivatives 506 is shown in Scheme 86. Ionic 1,3-dipolar cycloaddition of the appropriate azide 503 to ethyl phenylacetates gives l-(2-nitrophenyl)-4-aryl-5-oxo[l,2,3]triazoles 504. Catalytic reduction of these compounds affords the corresponding amines 505. Cyclocondenzation of these amines to the final tricyclic compounds 506 is performed using triphosgene in anhydrous tetrahydrofuran solution at room temperature (Scheme 86) <2005JME2936>. 

W Konig, R Geiger. A new method for the synthesis of peptides activation of the carboxyl group with dicyclohexylcarbodiimide and 3-hydroxy-4-oxo-3,4-dihydro-1.2.3-benzotriazine. Chem Ber 103, 2034, 1970. 

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