Nitrile-isonitrile rearrangement

Isomorphic monomers, 19 762 Isoniazid, 25 798 Isonicotinic hydrazide, 21 103 Isonitrile complexes, platinum, 19 656 Isonitrile-nitrile rearrangement, 21 149 Isononanoic acid, physical properties, 5 35t Isononyl alcohol, properties of commercial, 2 12t... 

Rearrangements. Both [2,3]sigmatropic rearrangements and the isonitrile-nitrile rearrangement (for those a-substituted to a carboxylic acid derivative) have been effected with the aid of SmL. 

D. H. Shaw, H. O. Pritchard, Can. J. Chem. 1967, 45, 2749. A free-radical chain mechanism for the isonitrile-nitrile rearrangement in solution was definitely claimed by Riichardt in 1983 M. Meier, C. Riichardt, Tetrahedron Lett. 1983, 24, 4671. Radical addition to isonitriles had been previously claimed by Shono T. Shono, M. Kimura, Y. Ito, K. Nishida, R. Oda, Bull Chem. Soc. Jpn. 1964, 37, 635. 

The isocyanide-cyanide (isonitrile-nitrile) rearrangement was discovered in 1873 by Weith and is best described as a cationotropic 1,2-shift. 

According to Scheme 4 elimination of a proton from the iminodiazonium ion (I) forms the nitrile. Rearrangement of the ion (I) leads to formanilide. But there are no data available supporting these ideas. Another possible way for the formation of nitrile is a rearrangement of the iminocarbonium ion (II) of the type which occurs in the isomerization of isonitriles to nitriles". It was found that in 71.2-90.4% sulphuric acid, phenyl isocyanate is converted quantitatively into formanilide. For a better understanding of the... 

In addition to these common types of reactions, several syntheses are known in which HFA causes changes in the substrate (e.g., isomerization of nitriles to isonitriles) or rearrangements of initially unstable products. However, only few exceptions to the above-mentioned examples have been found so far in HFA chemistry. 

Normally difficult nucleophilic displacements on hexachlorocyclotriphosphazene are facilitated by 18-crown-6 ether. Moreover, the displacement of Cl by CN apparently proceeds by formation first of the isonitrile which rearranges on standing to the nitrile. 

In both the nitrile and isonitrile complexes rapid reaction techniques indicate that protonation occurs at the ligand initially, but subsequent rearrangement yields a metal-hydride product. However, in both cases protonation is at the atom remote from the metal and so the transfer from ligand to metal must involve the proton either (i) sliding down the ligand or (ii) sequentially hoping from one atom to another as shown in the Figures 28 and 29. 

The migration (insertion) reaction may also occur in the case of many other unsaturated molecules such as SO2, CO2, N2, NO, nitriles, isonitriles, and ketones. The insertion of sulfur dioxide may proceed very rapidly. The NMR and IR measurements show that the reaction proceeds through O-sulfinates which subsequently undergo rearrangement to give stable S-sulfinates ... 

The dehydration of formamides leads to the formation of nitriles. This reaction can be classified as a homologation reaction, i.e., a reaction bringing about an increase in the hydrocarbon chain of an organic molecule. The transformation corresponds to dehydration to isonitrile, followed by rearrangement of the latter to nitrile. 

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