3- Substituted 1,2,3-triazole 1-oxides aromatic substitutions

The aromatic 2-substituted 1,2,3-triazole 1-oxides are represented by the structure 341. The parent compound 342 is one of the three possible tautomeric forms of 1-hydroxy-l,2,3-triazole 343. 1-Hydroxy-l,2,3-triazoles 343 constitute a separate group of compounds, which are not included in the present review (Scheme 101). 

The aromatic 3-substituted 1,2,3-triazole 1-oxides 448 are derived from 1-substituted 1,2,3-triazoles 457 by appending an oxygen atom to the... 

Substituted 1,2,3-triazole 1-oxides 448 have been reported to undergo electrophilic and nucleophilic aromatic substitution and are subject to debromination, proton-metal exchange, and halogen-metal exchange followed by electrophilic addition. Transmetallation and cross-coupling have not been described. 3-Substituted 1,2,3-triazole 1-oxides 448 can be proton-ated or alkylated at the O-atom and they can be deoxygenated and deal-kylated. The individual reactions are described in Section 4.2.7.1-4.2.7.14. 

The mechanism of the RuAAC reaction has been investigated by several groups and is summarized in Scheme 9.6. The proposed catalytic cycle includes the formation of the catalytically active species [Cp RuCl] and the formal substitution of the spectator ligands by the alkyne 40 and the azide 41 to give complex 42. After oxidative coupling of the alkyne and the azide, the intermediate species 43 undergoes reductive elimination and releases the aromatic triazole product 45. 

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