Catalyst-free activation of methylene chloride and alkynes by amines in a three-component coupling reaction to synthesize propargylamines

Abstract

Propargylamines are synthesized via metal-free activation of the C–halogen bond of dihalomethanes and the C–H bond of terminal alkynes in a three-component coupling without catalyst or additional base and under mild reaction conditions. The dihalomethanes are used both as solvents as well as precursors for the methylene fragment (C₁) in the final product. The scope of the reaction and the influence of various reaction variables has been investigated. A plausible reaction mechanism is proposed and the involvement of various intermediates that can be generated in situ in the process is discussed. The metal-free conditions also make this protocol environmentally benign and atom economical.