Palladium N-heterocyclic carbene catalyzed regioselective thiolation of 1-aryl-3-methyl-1H-pyrazol-5(4H)-ones using aryl thiols

A palladium N-heterocyclic carbene [Pd(NHC)Cl2] complex of Vitamin B1 developed earlier in our lab was also found to be an effective catalyst for regioselective thiolation via C-H bond activation of 1-aryl-3-methyl-1H-pyrazol-5(4H)-ones 1a-c using aryl thiols 2a-e. The protocol was found to be simple, efficient and highly regioselective to afford the target products 3a-o in good to excellent yields.

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