C-H bonds as ubiquitous functionality: preparation of multiple regioisomers of arylated 1,2,4-triazoles via C-H arylation.

We describe a general approach for the synthesis of complex aryl 1,2,4-triazoles. The electronic character of the C-H bonds and the triazole ring allows for the regioselective C-H arylation of 1-alkyl- and 4-alkyltriazoles under catalytic conditions. We have also developed the SEM and THP switch as well as trans-N-alkylation, which enable sequential arylation of the triazole ring to prepare 3,5-diaryltriazoles. This new strategy provides rapid access to a variety of arylated 1,2,4-triazoles and well complements existing cyclization methods.