Carbon-nitrogen groups, insertion

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. 

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. 

Reductive eliminations from nickel(ll) complexes to form carbon-heteroatom bonds in amines and ethers have also been reported. Like the mechanisms for oxidative additions to Ni(0) and Pd(0) that cleave carbon-heteroatom bonds, the mechanisms for reductive elimination from nickel(II) and palladium(II) complexes to form caibon-heteroatom bonds are different from each other. Most reductive eliminations from Ni(II) to form carbon-nitrogen bonds occur after oxidation of the Ni(II) to Ni(III) with ferro-ceruum, oxygen, or iodine (Equations 8.53 and 8.54). Reductive eliminations from Ni(II) to form carbon-oxygen bonds in ethers also requires oxidation of ttie Ni(II) to Ni(III) (Equation 8.55). In contrast, reductive eliminations from Ni(II) to form the ester group of a lactone occurred after a proposed insertion of CO into the nickel-carbon bond of an oxametallacycle without oxidation. Reductive eliminations from isolated arylnickd complexes to form amines and ethers have not been reported. 

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