Nitriles 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... 

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... 

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. 

The PdCli-catalyzed instantaneous rearrangement of A -carbethoxy-S-azabi-cyclo[5.1.0]oct-3-ene (60) takes place at room temperature to give A -car-bethoxy-8-azabicyclo[3.2.1]oct-2-ene (61)[50], The azepine 62 undergoes a smooth skeletal rearrangement to give 63, and the diazepine 64 is converted into the open-chain product[51]. Beckmann fission of the oxime 65 of ketones and aldehydes to give the nitrile 66 is induced by a Pd(0) complex and oxygen [52,53]. 

In addition to the nitrile and alcohol routes for fatty amine preparation, processes have been described by Unocal and Pennwalt Corporation, using an olefin and secondary amine (14—16) by Texaco Inc., hydrogenation of nitroparaffins (17—20) by Onyx Corporation, reaction of an alkyl haUde with secondary amines (21,22) by Henkel Cie, GmbH, reduction of an ester in the presence of a secondary amine (23) by catalytic hydroammonolysis of carboxyhc acids (24) and by the Hofmann rearrangement (25). 

Vapour phase pyrolysis of sulfoximides (529) results in the formation of the nitriles (530) (75JCS(Pl)4l). The tosylate (273), when treated with acetic anhydride, rearranges to (531)... 

However, the thermolysis of diacylfuroxans (429) yielded two types of nitrile Af-oxides. An uncrowded diacylfuroxan such as (429a) rearranged to the a- acyloximino nitrile A-oxide (430) the diacylfuroxan with bulky substituents such as in (429b) gave rise to the half molecule acyl nitrile Af-oxide (431). Both types of nitrile Af-oxides (431) and (430) have been trapped with DMAD and hexafluoro-2-butyne to give isoxazoles in good yield. These reactions are shown in Scheme 97. 

Rahman and Clapp decomposed dinitromethane derivatives in DMF in the presence of alkenes to obtain 2-isoxazolines. Without any alkene present, an acid and KNO2 were obtained. They proposed a mechanism which proceeded via a three-membered ring or a nitrocarbene which rearranged to a nitrile oxide (76JOC122, 75MI41612). 

The 1-azirines obtained from the vapor phase pyrolysis of 4,5-disubstituted 1-phthalimido-1,2,3-triazoles (157) have been found to undergo further thermal reactions (71CC1S18). Those azirines which contain a methyl group in the 2-position of the ring are cleaved to nitriles and phthalimidocarbenes, whereas those azirines which possess a phenyl substituent in the 2-position rearrange to indoles. 

Better yields are attributed to intimate association of the basic nitrile group at the surface of the mtrosomum salt causing nitrosative decomposition of the azide to occur in close proximity to the weakly nucleophilic complex fluoride anion Fluorination yields can be further enhanced to 59-81% by lengthening the azido nitrile chain, but the reaction is accompanied by pronounced secondary fluoronitnle formation arising from rearrangement [100, 101] (Table 8)... 

Extensions of 1,3-dipolar additions of aromatic azides (720,721) to other enamines (636), and particularly to the enamine tautomer of SchilTs bases, were explored (722,723). Further nitrone additions were reported (724,725) and a double nitrile oxide added to an endiamine (647). Cyanogen azide and enamines gave cyanoamidines through rearrangement (726). 

A further type of nitro-group rearrangement gives rise to a cyclic hydroxamic ether. Noland e.t aL describe the action of cold, dilute sulfuric acid on the sodium salt of 5-nitronorbornene (98), which results in conversion to the oxazinone (101). This complex rearrangement is rationalized by the sequence 98 101 involving intermediate formation of the nitrile oxide (99) and the hydroxamic acid (100). 

The electron impact positive ion spectrum of l,2,5-oxadiazolo[3,4-/]quinoline IV-oxide 46 shows the loss of N2O2 from the molecular ion, a process that must be followed by a substantial rearrangement to enable the observed loss of propyne-nitrile. This remarkable result apparently arises through a series of H-atom shifts which relocate the dehydroaromatic moiety in the heteroring (890MS465). 

The ketoxime derivatives, required as starting materials, can be prepared from the appropriate aromatic, aliphatic or heterocyclic ketone. Aldoximes (where R is H) do not undergo the rearrangement reaction, but rather an elimination of toluenesulfonic acid to yield a nitrile. With ketoxime tosylates a Beckmann rearrangement may be observed as a side-reaction. 

Fusion of an all cyclic ring onto the piperidine so as to form a perhydroisoquinoline is apparently consistent with analgesic activity. Synthesis of this agent, ciprefadol (68), starts with the Michael addition of the anion from cyclohexanone 56 onto acrylonitrile (57). Saponification of the nitrile to the corresponding acid ( ) followed by Curtius rearrangement leads to isocyanate Acid... 

The diazepine 26 reacts with the stable nitrile oxide 27 to yield the cycloadduct 28, accompanied by a trace of the rearranged adduct 29.102... 

---