Synthesis of Substituted Pentafluorosulfanylpyrazoles Under Flow Conditions.

The development of flow conditions for the synthesis of pentafluorosulfanylpyrazoles is reported. A range of alkyl- and aryl-substituted SF-alkynes were used in combination with different diazoacetates for this transformation. The corresponding substituted SF-pyrazoles were obtained in up to 90% yield (average of 74% for 21 examples) as a mixture of isomers (up to 73:27 ratio). Synthetic transformations starting from an SF-containing pyrazole were also demonstrated.