Convenient and versatile synthesis of 3-(polyfluoroalkyl)pyrazoles

Abstract

3-(Polyfluoroalkyl)pyrazoles 4 have been synthesized in excellent yields in a two-step sequence from poly-fluoroalkyl iodides 1. The synthesis consisted of the reaction of iodides 1 with enamines or enol ethers to give α-polyfluoroalkyl carbonyl derivatives 3 followed by treatment with hydrazine monohydrate. A practical one-pot synthesis of pyrazoles 4 directly from iodides 1 has also been developed and the reaction mechanism is discussed.