Carbon-nitrogen groups, insertion reactions

Additional support for the carbon monoxide-alkoxycobalt insertion reaction is found in the reaction of tert-butyl hypochlorite with sodium cobalt carbonyl. This reaction, if carried out at — 80°C. in ether solution under nitrogen or carbon monoxide, leads to about a 10% yield of /er/-butoxycarbonylcobalt tetracarbonyl which has been isolated as the monotriphenylphosphine derivative. The major product seems to be cobalt octacarbonyl, possibly formed by decomposition of an intermediate JerJ-butoxycobalt tetracarbonyl (34). This reaction appears to be a true insertion reaction although a direct attack of a coordinated carbonyl group upon oxygen cannot be ruled out. 

Recently an arsenic amide derivative has reacted with an isocyanate, adding across the carbon—nitrogen double bond. I think this is the first example of a group V element which seems to be undergoing an insertion reaction. 

Reactions with other carbon triple bonded functional groups. The substitution of nitrile for alkynes does not lead to pyridines or quinolines in the benzannulation reaction.Instead noncyclic products are obtained that are the result of insertion of the carbon-nitrogen triple bond into the metal-carbene bond. On the other hand, in a very recent report it was found that X -phosphaalkynes will undergo the benzannulation reaction to produce phosphaarene chromium tricafbonyl complexes. 

The CO insertion [reaction (g)] into the metal-carbon bond of the nickel(II) complex produces an unstable acyl intermediate, which undergoes a rearrangement to a nickel(O) complex, presumably via reductive elimination of the acyl group from nickel to nitrogen. ... 

These compounds exhibit IR bands at 2130 cm" that are due to coordinated isocyanide and at 1580-1620 cm" due to the carbon-nitrogen stretching vibration of the alkyl-imino group. A possible mechanism of this reaction includes primary phosphine dissociation, followed by isocyanide coordination and migratory interaction of the alkyl and the isocyanide. This mechanism is similar to that proposed for the CO insertion. 

Multiple, successive insertion of isonitriles into the palladium-carbon o--bond has also been found with organopalladium(II)bis(phosphine) complexes. However, unlike the Ni- catalyzed polymerization, only single, double, and triple insertion reactions of isonitriles have been reported for Pd-mediated reactions. For instance, reaction of methylpalladium(II) complex 2 with cyclohexyl isonitrile in ratios of 1 1, 1 2, and 1 3 afforded selectively single (3), double (4), and triple (5) insertion products, respectively (Scheme 3). However, no further insertion of cyclohexyl isonitrile to 5 took place. No reactivity of the triple insertion complex 5 was explained by the intramolecular coordination of the nitrogen atom of the third imino group, which formed a stable five-mem-bered chelating palladium complex. 

Figure 5.16 Photoactivation of a phenyl azide group with UV light results in the formation of a short-lived nitrene. Nitrenes may undergo a number of reactions, including insertion into active carbon-hydrogen or nitrogen-hydrogen bonds and addition to points of unsaturation in carbon chains. The most likely route of reaction, however, is to ring-expand to a dehydroazepine intermediate. This group is highly reactive toward nucleophiles, especially amines.

Aromatic dicarboximides behave in a different way on irradiation with aikenes. Instead of cycloaddition to the carbon-oxygen double bond, the overall reaction gives a product in which the alkene is inserted between the nitrogen atom and one of the carbonyl groups (4.78). The reaction is stereospecific, and the mechanism may... 

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