1- Aminobenzotriazole, oxidation

Oxidation of 1 -aminobenzotriazole also yields benzyne under mild conditions. An oxidized intermediate decomposes with loss of two molecules of nitrogen. ... 

Methods such as the pyrolysis of (106), that do not require strongly basic conditions, have been used to generate arynes in bulk for preparative purposes, and another, even better, method is oxidation of l-aminobenzotriazole (107) with lead tetraacetate ... 

Oxidation of 1-aminobenzotriazole (283) among other products results in the formation of bistriazolo compound 284. This reaction involves a benzene intermediate and illustrates an example wherein IBD behaves differently than lead tetra-acetate, which in this case gives biphenylene [80JCR(S)303] (Scheme 71). 

The addition of benzyne to Cgg leads to the formation of [2+2] qfcloadducts [330-332]. The in situ generation of benzyne can be achieved by diazotization of anthraniKc acid at room temperature with isoamyl nitrite, by diazotization of the potassium salt of anfhranilic acid in the presence of 18-crown-6, or by the oxidation of 1-aminobenzotriazole with lead tetraacetate (Scheme 4.54). Adduct formation occurs in the 1,2-position, leading to the corresponding ring-closed structure. 

Phenanthridinones.1 Benzyne, generated in situ by Pb(OAc)4 oxidation of 1-aminobenzotriazole (l),2 undergoes [4 + 2]cycloaddition to cyclic vinyl isocyanates to form phenanthridinones. 

Oxidative rearrangement of 1-aminobenzotriazole yields the reactive 1,2,3-benzotriazine which reacts with dienophiles to produce quinolines (Scheme 70) <1998CPB332>. 

Lead tetraacetate oxidation of 3-amino-5-(-butyl-1,2,3-triazolo[4,5-d]pyrimidine (74), as in the case of 1-aminobenzotriazole, leads to a pyrimidyne intermediate which may be trapped using a... 

Benzyne, generated either by oxidation of 1-aminobenzotriazole with lead tetraacetate or by decomposition of benzenediazonium-2-carboxylate, was efficiently trapped by (2) to give 88% of the 1,2-benzisoselenazole (26) however, it was trapped in only 5-10% yield by (1). The series of adducts analogous to (26), prepared from benzyne and substituted benzoselenadiazoles (81JCS(P1)607), occurred via attack of the benzyne at the selenium atom followed by reorganization of the intermediate according to Scheme 6. Benzyne addition to dimethylthiadiazole produced methyl derivatives of quinoline and 1,2-benzisothiazole (82CC299). 

Another method of producing benzyne is from the decomposition of 1-aminobenzotriazole, after it has been oxidised with lead tetraacetate. The oxidation converts the amino group to the nitrene intermediate, and this fragments. Even though there is some doubt over whether nitrenes can exist as true intermediates in these circumstances, suggest a mechanism that utilises their involvement in order to achieve the desired result. 

An interesting reaction is the N-amination by the reagent of benzotriazole (1) to give 1-aminobenzotriazole (2)," a compound of particular interest as a benzyne precursor (.tee Lead tetraacetate, miscellaneous oxidations). 

Campbell and Rees report that benzyne can be generated rapidly and almost quantitatively under mild conditions by oxidation of 1-aminobenzotriazole with lead tetraacetate in benzene. The nitrene (2) presumably is an intermediate. When... 

Lead tetraacetate oxidizes 2-aminobenzotriazole (4) to cis,cis-muconitrile (7) in 64% yield, presumably through the nitrenes (5) and (6). The same product is obtained in 50% yield by lead tetraacetate oxidation of o-phenylenediamine (8). ... 

The analog of 4 with a sulfinate group replacing the carboxylate exists in the ring-closed form 8 it decomposes in solution at 10°C to give benzyne, nitrogen, and sulfur dioxide.15 Oxidation of 1-aminobenzotriazole (9) with lead tetraacetate or other oxidants is another efficient source of benzyne via fragmentation of the intermediate nitrene 10.16... 

The lead tetraacetate oxidation of 1-aminobenzotriazole leads to benzyne (Eq. 107), whereas 2-aminobenzotriazole ring opens to Z,Z-mucononitrile (Eq. 108).398... 

Benzyne is also formed almost quantitatively on oxidation of l-aminobenzotriazole with NBS (2 equivalents) in the presence of tetracyclone, 1,2,3,4-tetraphenylnaphthalene is obtained in 88% yield. In the absence of a trap, o-dibromobenzene is obtained in 52% yield. No dimer is formed. Bromine is known to be an efficient scavenger of benzyne generated from this precursor.3... 

Oxidation of heterocyclic amino derivatives yields various reaction products depending on the structure of the amine. 4-Benzylamino-3-methyl-4//-1,2,4-triazole is oxidized with DCT in chloroform to give the azomethine derivative 110 (69ZC325). l-Amino-4,5-diphenyl-l,2,3-triazole under the action of CBT forms diphenylacetylene 2-aminobenzotriazole yields cis, cw-l,4-dicyanobuta-l,3-diene and 1-aminobenzotriazole yields a mixture of chlorobenzene and o-dichlorobenzene. Oxidation of 1-aminobenzotriazole in the presence of tetraphenylcyclopentadienone leads to 1,2,3,4-tetraphenylnaphthalene via benzyne intermediate [68JCS(CC)1305 69JCS(C)1474] (Scheme 101). 

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