A study on the insertion of isocyanides into palladium allyl bond: Effect of their nature on the strategic steps of the process

The coordinative capabilities of tert-butyl isocyanide (TIC) and 2,6-dimethylphenyl isocyanide (DIC) were shown to be perfectly comparable in spite of their different steric and electronic features. As a matter of fact, when equimolar amounts of these two isocyanides are made to compete for the same coordination sites of a Pd-allyl substrate the statistical mixture of the possible products is always observed. contrary, the DIC proved to be much more efficient than TIC in promoting the migratory insertion of an allyl fragment. This conclusion was simply based on the analysis of the products resulting from the reaction of an appropriate Pd-allyl complex with both isocyanides simultaneously.