Interactions between 1, 3-Dipoles and Metal Ions. Stereo- and Regiocontrol of 1, 3-Dipolar Cycloaddition Reactions

Abstract

This review focuses on our own attempts of metal ion-assisted stereo- and regiocontrol of 1, 3-dipolar cycloaddition reactions : N-Metalated azomethine ylides, or metal enolates, of alkylideneamino nitriles and esters undergo endo-selective cycloadditions to α, β-unsaturated carbonyl acceptors to give 1-pyrrolines and pyrrolidines. Magnesium allylic alkoxides are highly reactive in nitrile oxide cycloadditions which are exclusively syn-selective and regioselective. Equally fruitful are nitrone cycloadditions to allylic alkoxides and Lewis acidcatalyzed nitrone reactions with allylic alcohols and enones.