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 SF5-alkynes were used in combination with different diazoacetates for
this transformation. The corresponding substituted SF5-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 SF5-containing pyrazole were also demonstrated.