Coupling of allylic halides promoted by iron metal dispersed in dimethyl formamide

Abstract

The coupling reaction of allylic halides to produce non-conjugated dienes was investigated. It was found that iron powder could be utilized, without any special pretreatment, to promote the coupling reaction when a dipolar aprotic solvent was employed as the reaction medium.Effects of variables such as the nature of the halogen atom in the reactive position of the substrate, substituents on the substrate, presence or absence of organic or inorganic halide catalysts, and solvent type were explored briefly.Non-conjugated dienes can be prepared in yields which exceed 90% in the more favorable cases. The present procedure avoids many of the difficulties inherent in such previous methods as the Grignard reaction or the nickel carbonyl-promoted reaction.