Nucleophilic attacks isocyanide complexes

The stereocontrol observed in these reactions is rationalized on the basis of zinc complexes formed with the Schiff bases, as described in Section 1.4.4.2.2. The isocyanide, being a free and potent nucleophile, attacks this complex from the sterically less-hindered side, that is. from the side of the ring oxygen. 

The reactions of nucleophilic reagents with cationic and uncharged metal carbonyl complexes have received much attention in the past, and it is not surprising that these studies have now been extended to isocyanide metal complexes. Different products in these reactions can arise by three general routes these include ligand substitution, reactions involving attack at a ligand, and reduction of the metal complex. All have been observed in reactions with metal isocyanide complexes. 

The susceptibility of a metal complex to nucleophilic attack is enhanced by a positive charge on the complex. This fact, and the fact that most metal isocyanide complexes are cationic, probably explains why no nucleophilic reactions of uncharged isocyanide complexes have yet been reported. It is... 

The p-functionalized 2-hydroxyphenyl isocyanide not only contains the isocyanide and the nucleophile within the same molecule, but both functional groups are also arranged in one plane for an intramolecular nucleophilic attack [176]. This arrangement, in addition to the aromaticity of the five-membered ring obtained after cyclization to the carbene ligand, particularly favors the intramolecular nucleophilic attack. In contrast to 2-hydroxyethyl isocyanide, free 2-hydroxyphenyl isocyanide is not stable [177]. The stable 2-trimethylsiloxyphenyl isocyanide [178] can serve as a synthon for 2-hydroxyphenyl isocyanide. Carbene complexes 63 with an NH,0-stabilized NHC ligand can be obtained from the complexes 62 with the... 

N==Ca+—Aua which makes the isocyanide ligands susceptible to nucleophilic attack and has led to formation of carbene complexes, iminoalkyl complexes and catalytic conversion of isocyanides to formamidines using alkyl or aryl isocyanide complexes of gold(I).301,402 4(y7-409-415 A review of this significant work has been published.16... 

Complexes containing unusual isocyanide ligands have evolved from attempts to alkylate the anions [M(CN)6]4 (M = Fe, Ru, Os) with [Et3OJBF4 in acetone solution. The compounds isolated [M CNCMe2 CH2COMe)6](BF4)2 resulted from an initial acid-catalyzed aldol condensation of the acetone solvent followed by a nucleophilic attack of the carbon-... 

A cyclopentadienylcopper-fcr/-butyl isocyanide complex catalyzes the Michael addition of dimethyl methylmalonate to acrylonitrile at room temperature to give an S6% yield of the adduct 249). As the CU2O—BNC complex can also catalyze the addition of indene to methyl acrylate, the intermediate is most likely an organocopper complex. The reactions and kinetic data support the mechanism given by Eq. (118) to (120), involving metalation and nucleophilic attack by the carbanion on the olefin within the complex. Displacement of a solvent ligand by the olefin and coordination of the latter to the copper species are essential features of the mechanism. The rate of reaction is decreased if the compound with the... 

The nucleophilic attack of HS on the mixed carbonyl isocyanide complex 301 (R =p-tolyl) takes place on the carbon of the isocyanide ligand and gives the r-bound / tolylisothiocyanate 302, whereas MeO attacks at... 

In Nolte and Drenth s nickel catalyzed system, the polymerization was believed to be initiated by a nucleophilic attack by the alcohol used as a solvent or the halide on the starting complex on the coordinated isocyanides. Successful asymmetric polymerization was achieved using a dicationic tetrakis(isocyanide)nickel(II) complex 46 with enantiopure primary amines, which served as a chiral nucleophile in the initial step (Scheme 35) [58, 59]. In a typical experiment, a catalyst prepared from (f-BuNC)4Ni(II)(C104)2 (46a) (1 mol%) and an optically active amine (1 mol%), was used for polymerization of isocyanides with, or without a solvent, such as n-hexane, in... 

Palladium isocyanide complexes react with amines and alcohols to give palladium Carbene Complexes (equation 15) in a reaction that is a nucleophilic attack on the isonitrile carbon. These complexes easily lose a halide if it is trans to the carbene ligand, since the carbene carbon has a high trans influence. The structures of these compounds have the carbene carbon and its two heteroatom groups in one plane, which is perpendicular to the coordination plane of the Pd. 

An unsymmetrically substituted bis(carbene)platinum(li) complex 87 was obtained by consecutive nucleophilic attack of propanol and then propylamine onto /ra j--diiodo(bis-isocyanide)platinum(ll) complex.The stable complex gave rise to a N phase (Cr 142 N 173 I). 

Just like the isoelectronic carbon monoxide, an isocyanide is an excellent ligand to metal ions. The chemistry of metal isocyanide complexes has been reviewed by Singleton and Oosthuizen. Only a few examples will be given here. Insertion of an isocyanide into a metal-carbon bond frequently occurs. It is not always clear whether the key step is electrophilic or nucleophilic attack on the coordinated isocyanide or whether the reaction is concerted. Insertion into metal-carbene and metal-carbyne complexes have been reviewed by Aumann. Coordination to the metal considerably affects the chemistry of the isocyanide. If the metal is electron-donating, as in nitrogenase-like centres, the coordinated isocyanide is apt to electrophilic attack at nitrogen cf. Section III. 

Most metals are electron-attracting with respect to isocyanide ligands and the coordinated ligand is sensitive to nucleophilic attack. This reversal in behaviour is called Umpolung , a term introduced by Seebach . Umpolung is an important feature in organometallic chemistry. An example of such a nucleophilic attack is the initiation step in the polymerization of isocyanides by nickel(II) complexes ... 

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