Isonitriles isomerization

Earlier work [151] showed that at high temperature, isonitriles isomerize into nitriles. Isonitriles have recently [152] been isomerized at much lower temperatures by reacting them with alkyl lithium or Grignard reagents. Ketones are simultaneously formed in amounts which vary with the structure of the alkyl—... 

Loss of PhH by reductive elimination, binding of substrate via the iso-nitrile C, cyclometallation of the ArCH3 group, migratory insertion involving the isonitrile, isomerization and reductive elimination of the product. 

Cyanomethane, commonly known as acetonitrile, CH3CN, is a toxic volatile liquid that is used as a solvent to purify steriods and to extract fatty acids from fish oils. Acetonitrile can be synthesized from methyl isonitrile by the isomerization reaction CH,NC(g) - CH3CN(g). 

A very common combination in Pd-catalyzed domino reactions is the insertion of CO as the last step (this was discussed previously). However, there is also the possibility that CO is inserted as the first step after oxidative addition. This process, as well as the amidocarbonylation, the animation, the arylation of ketones, the isomerization of epoxides, and the reaction with isonitriles will be discussed in this section. 

Propargylated tosylamides also isomerize efficiently [221, 281]. On the other hand, rare examples are propargylated hydrazines [251], N-propargylated imines [282], isonitriles (must be N-propargylated) [283], ammonium salts [284] and azides [285],... 

In addition, we should note that data of H, NMR spectroscopy, mass-spectra, and elemental analysis given in [138] did not contradict the structure of compound 98, being regioisomer of 97. The similar situation had already been shown in the synthesis of 3-aminoimidazo[l,2-a]pyrimidines [139]. Mandair et al. carried out the model MCRs of 2-aminopyrimidine with several aldehydes and isonitrile components in the methanol under the ambient temperamre with the various catalysts. As a result, 3-aminoimidazo[l,2-a]pyrimidine and position isomeric 2-aminoimidazo[l,2-a]pyrimidines were isolated from the reaction mixture in different ratio (Scheme 45). The stmctures of the isomers obtained in this case were confirmed by the X-ray diffraction analysis, as well as the structures of the side-products isolated. 

Lever has successfully predicted Mn"/ potentials of 24 Mn-carbonyl complexes containing halide, pseudohalide, isonitrile, and phosphine co-ligands, with additivity parameters derived from the potentials of Ru "/" couples [39]. An important consideration for heteroleptic complexes is the influence of isomerism on redox thermodynamics. For Mn(CO) (CNR)6- complexes, with n = 2 or 3, the Mn"/ potentials for cis/trans and fac/mer pairs differ by as much as 0.2 V [40]. The effect arises from the different a-donor and 7r-acceptor abilities of carbonyl (CO) and isocyanide and their influence on the energy of the highest energy occupied molecular orbital (HOMO). 

In a simple displacement of benzyl isonitrile by K14CN from II, all the labeled atoms should appear in the isonitrile complex and none in the benzyl isonitrile. But the label was present in all of the products isolated and in each to a different extent. For example, the benzyl isonitrile was more radioactive than the N-benzyl formamide which must have been formed by addition of water to benzyl isonitrile. The results indicate that the internal isomerization (III V, Equation 7), the generation of benzyl isonitrile and N-benzyl formamide, and the polymerization of benzyl isonitrile are concomitant reactions. 

When an isonitrile ligand containing a suitable hydroxyl group was reacted with AUCI4, it underwent isomerization (147) via a carbene complex (Scheme 1). With CN(CH2)3OH, in the presence of a noncoordinating anion, the bis(carbene)gold(I) complex [Au tO(CH2)3l(jH 2]+BPhJ was formed. 

For compounds containing bridging isonitrile groups a further source of isomerism and stereochemical nonrigid behavior is the orientations of the alkyl or aryl groups, which can give rise to syn (32) and anti (33) isomers (65). 

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... 

Imidate salts hydrolysis, 118-144 syn and anti, 120 isomerization, 142 B-lactam, 142 Iminium salts, 211-221 Imino-ethers, 147 lodolactonization, 169 Ionic state of tetrahedral intermediates, 65, 105-106, 119 Ionophore A-23187, 13 Isochromane-3-one, 70 Isocyanate, 300 Isonitrile, 296... 

Palladium-mediated cydization based on the reactivity of o-alkynyl or alkenyl-phenyl isonitriles have been developed [105]. On the basis of their earlier studies on the three-component synthesis of allyl aryl cyanamides [106], Yamamoto and co-workers reported a palladium-catalyzed three-component coupling reaction of 2-alkynylisocyanobenzenes 122 with allyl methyl carbonate and trimethylsilylazide leading to N-cyanoindoles 125 [107]. One of the key steps of the proposed mechanism is the formation of 7i-allylpalladium carbodiimide 123 and its isomerization to rc-allylpalladium cyanamide complex 124 (Scheme 8.50). 

Further derivatives of amines in which the a-C,H groups are sufficiently acidic to enable metalation are carbamates [235,238-240] (Scheme 5.26), imides[241], N-nitroso amines [59,242], ureas [201,243], some N-phosphorus derivatives [212, 214, 226, 244, 245], N-(2-pyridyl)amines (Scheme 5.26), and isonitriles [59]. A potential side reaction in the examples in Scheme 5.26 is the lithiation of the arene this is, in fact, observed with an isomeric dipyridopyrazine (last reaction, Scheme5.26). 

Stable bisamino silylenes such as 83 and 85 react with organo substituted isonitriles by insertion into the N-C bond to afford exclusively silanitriles (e.g., 160) which have tetracoordinated silicon atoms <1998POL999, 2000ACR704>. In particular, no silaketenimines, the products of simple addition of the silylenes to the isonitriles, were detected. The reaction between 83 and pivaloyl isonitrile is thought to proceed via insertion of the silylene in the N-C bond and isomerization of the silaisonitrile 161 to the silanitrile 160 (Scheme 20). In the case of silylene 85 the outcome of the reaction depends on the actual conditions. Excess of silylene 85 during the course of the reaction affords product 162, which results from the addition of 2 equiv of silylene 85 to the isonitrile <2001JOM209>. 

Spectroscopic data show that the olefin monocyanocarbonylferrates and -ruthenates and their derived isonitrile complexes occur as two isomeric forms, in which the CN or isonitrile ligand occupies either an apical or basal position in a square-pyramidal structure. 

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. 

As in the case of cyanophosphanes (Section III,A,8), isomerization of the nitriles to the isonitriles is the initial step. While triisocyanatoarsane proved to be inert to HFA (176), the expected product 81b with triisothiocyanato-arsane has been isolated (240). The structure of 81b is reported. 

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