Amines carbon-nitrogen bond cleavage

Kadin, S. B.. Monomethylation of aromatic amines via sodium borohydride. Mediated carbon-nitrogen bond cleavage, 7. Org. Chem.. 38, 1.348, 1973. 

Sultams like (190) undergo aminolysis with amines by nitrogen-sulfur bond cleavage (similar to hydrolysis), and suitably functionalised sultams (191) may also suffer carbon-nitrogen bond cleavage by a bimolecular (E2) elimination reaction (Scheme 79). 

When heated with benzene in the presence of AICI3, OOiV-trialkyl phosphoramidates suffer both carbon-oxygen and carbon-nitrogen bond cleavage, and afford mono- or di-alkylbenzenes. When, on the other hand, 00-diphenyl iV-(cyclo)alkyl phosphoramidates or AWW"-trialkyl phosphoric triamides are employed, only carbon-nitrogen bond cleavage takes place, and no reaction occurs with most amides from secondary amines. ... 

Aliphatic and aromatic amines are also widely available from nature or industry. However, studies on their chemical transformation through transition metal-catalysed carbon-nitrogen bond cleavage are relatively scarce. Recently, several nickel-catalysed transformation of amine derivatives including aryl or benzylammonium salts, N-atyl amides and carbamates, as well as JV-sulfonyl aziridines were reported. 

The Hofmann elimination of amines has been used to elucidate the structure of nitrogen-containing natural products, such as alkaloids (Section 25-8). Each sequence of exhaustive methylation and Hofmann elimination cleaves one C-N bond. Repeated cycles allow the heteroatom to be precisely located, particularly if it is part of a ring. In this case, the first carbon-nitrogen bond cleavage opens the ring. 

Oxidative reactions at carbon predominate in the biotransformation of cyclic amiiies, and an important consequence of this is often the cleavage of the carbon-nitrogen bond. For example, A-dealkylation of N- alkyl substituted pyrrolidine (or piperidine, morpholine, etc.) involves an initial oxidative attack at the a- alkyl carbon atom to yield an N hydroxyalkyl derivative (carbinolamine), which is then metabolized to a secondary amine and the corresponding aldehyde. The metabolic conversion of nicotine to nornicotine (30 see Scheme 3) probably involves this mechanism, although the iminium ion (31) has also been suggested as an intermediate in the biotransformation (76JMC1168). Carbinolamines are unstable intermediates and have been identified only in a few cases, e.g. A-hydroxymethylcarbazole... 

Typical examples for type 2 are the cleavage of the carbon-oxygen bond in benzylic ethers (X = OR) either directly or indirectly via triarylamine cation radicals [49] (Eq. 22.42), the cleavage of the carbon-nitrogen bond in amines (X = NR2) [50] (Eq. 22.43), and the cleavage of the carbon-sulfur bond in sulfides (X = SR) [51] (Eq. 22.44) ... 

RNH, — R,NH + NH,. N-Mono- and di-substituted amides yield secondary and tertiary amines, respectively however, considerable cleavage of the carbon-nitrogen bonds occurs. ... 

Deamination via sulphonamide intermediates allows the conversion of the carbon-nitrogen bond into the carbon-oxygen bond. Conditions have been established such that nitrates may be obtained from the deamination of primary amines with dinitrogen tetroxide at low temperature rather than alcohols/ The oxidation of amines to nitriles has been carried out using copper(l) chloride in pyridine under an oxygen atmosphere/ which is a milder reagent than those previously used to perform this transformation. Cleavage of tertiary amines with ethyl chloroformate affords a simple preparation of di- and tri-substituted olefinic synthons (Scheme... 

This may be explained by considering the nitration of hexamine with nitric acid as a stepwise degradation by nitrolysis, i.e. the nitration of amine involving the stepwise cleavage of the bond between the nitrogen and carbon atoms. According to Lamberton [39] this idea was first advanced by Linstead. The main work on this subject has been done by British [39] and Canadian [40] authors. 

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