Three-component synthesis of C₂F₅-substituted pyrazoles from C₂F₅CH₂NH₂•HCl, NaNO₂ and electron-deficient alkynes

A one-pot reaction between C₂F₅CH₂NH₂•HCl, NaNO₂ and electron-deficient alkynes gives C₂F₅-substituted pyrazoles in excellent yields. The transformation smoothly proceeds in dichloromethane/water, tolerates the presence of air, and requires no purification of products by column chromatography. Mechanistically, C₂F₅CH₂NH₂•HCl and NaNO₂ react first in water to generate C₂F₅CHN₂, that participates in a [3 + 2] cycloaddition with electron-deficient alkynes in dichloromethane.