One-Pot (3+2) Cycloaddition-Isomerization-Oxidation of 2,2,2-Trifluorodiazoethane and Styryl Derivatives

A facile access to5-aryl-3-trifluoromethylpyrazoles has been developedby a one-pot (3 + 2) cycloaddition-isomerization-oxidationsequence employing 2,2,2-trifluorodiazoethane and styryl derivatives.A broad variety of functional groups and good yields are achievedunder mild conditions. Additionally, the functionalization of 3-trifluoromethylpyrazoleswas studied. DFT calculations of the cycloaddition transition stateenergies are consistent with the experimentally observed reactivity.

Automated summary

A facile one-pot (3 + 2) cycloaddition-isomerization-oxidation sequence using 2,2,2-trifluorodiazoethane and styryl derivatives has been developed for the synthesis of 5-aryl-3-trifluoromethylpyrazoles. The reaction showed broad functional group tolerance and high yields under mild conditions. DFT calculations confirmed the reactivity observed experimentally by analyzing the transition state energies of the cycloaddition reaction.