The Nef Reaction of Isocyanides

The interaction of isocyanides with acyl chlorides was first reported by Nef in 1892. The resulting α-keto imidoyl chlorides may be hydrolyzed to form α-keto amides. Relatively few data are available on this reaction and the chemistry of α-keto imidoyl chlorides has been largely underestimated until some recent uses in intra­- and intermolecular couplings with a variety of nucleophiles. The present review brings a comprehensive presentation of the Nef reaction of isocyanides focusing on mechanism and regioselectivity issues. 1 Isocyanide Chemistry 2 Isocyanide Interaction with Acyl Chlorides and Analogues 2.1 General Considerations 2.2 Methods of Preparation of α-Keto Imidoyl Chlorides 2.3 Nef Reaction Mechanism 3 Reactivity of α-Keto Imidoyl Chlorides 3.1 General Behavior of α-Keto Imidoyl Chlorides 3.2 Intramolecular Trappings 3.3 Intermolecular Trappings and Three-Component Reactions 4 Extensions of the Nef Reaction 5 Conclusion