1,3-Dipolar Cycloaddition of SF5‑Alkynes with Nonstabilized Diazo: Synthesis of Highly Substituted SF5‑3H‑Pyrazoles

This work presents the 1,3-dipolar cycloaddition of SF5-alkynes with nonstabilized diazo compounds under mild conditions, producing highly substituted SF5-3H-pyrazoles. Eighteen examples are given, with yields of up to 91%. The two regioisomers were obtained in ratios ranging from 27:73 to 73:27. The products can undergo a Van Alphen–Huttel rearrangement. DFT calculations were performed to understand the selectivities and rearrangements.