Metal-Free Halogenation of N-Substituted Enaminoesters and Enaminones: A Facile Access to Functionalized α,α-Dihaloimines

An efficient and general method for the synthesis of functionalized α,α-dihaloimines via halogenation of N-substituted enaminoesters and enaminones is described. This reaction, in which both α,α-dihaloimines and mixed α,α-dihaloimines could be achieved in good to excellent yields, is believed to proceed via an α-monohalogenated enamine intermediate. This synthetic method features no use of transition metals, readily accessible substrates, mild reaction conditions, simple and safe operation, and gram scale synthesis. Furthermore, the synthetic utility of the products was demonstrated by their efficient transformations to further useful nitrogen-containing heterocycles and building blocks.