Mannich/Friedel–Crafts preparations of 1-(arylmethyl)benzotriazoles and synthetic transformations of their lithio derivatives

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Abstract
The synthesis of 1-(arylmethyl)benzotriazoles by Mannich type reactions of benzene, toluene, p-xylene and chlorobenzene with 1-chloromethylbenzotriazole in the presence of aluminium halides is reported. Alkylation, of their lithio derivatives followed by the cleavage of benzotriazole from the resulting 1-(α-arylalkyl)benzotriazoles upon reduction with LiAlH4–AlCl3 or elimination by AcOH are shown to be useful procedures for the preparation of substituted arenes. An oxidative coupling of lithiated 1-(arylmethyl)benzotriazoles gave 1,2-diaryl-1,2-di(benzotriazol-1-yl)ethanes. Novel heterocyclic ring fissions of the lithio derivatives of 1-(arylmethyl)benzotriazoles afforded 1,2,4-benzotriazine and 1,2-bis(N-methylanilino)ethene derivatives.