Direct synthesis of N2-substituted triazole and triazine derivatives has been a challenge in N-heterocyclic chemistry. Under copper(II) catalysis ketene N,S-acetals, that is, alkylthio-substituted enaminones, efficiently reacted with aryldiazonium salts to… Click to show full abstract
Direct synthesis of N2-substituted triazole and triazine derivatives has been a challenge in N-heterocyclic chemistry. Under copper(II) catalysis ketene N,S-acetals, that is, alkylthio-substituted enaminones, efficiently reacted with aryldiazonium salts to allow the regioselective generation of functionally diverse N2-substituted 1,2,3-triazoles and 2,3-dihydro-1,2,4-triazines. The oxidant and base-dependent reaction yielded the five- and six-membered N-heterocyclic products, respectively. The synthetic protocol features broad substrate scopes and good functional group tolerance under mild conditions. The mechanistic studies have revealed that the reaction proceeds via alkenyl azo/imino hydrazone intermediates.
               
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