Beckmann rearrangement Ritter reaction

We wish to report a new approach to condensation reactions of hydroxy compounds related to the Ritter reaction, the Beckmann rearrangement and peptide formation based on easily accessible pentaco-ordinate spirophosphoranes of the type (3) (6 - ). 

The participation of nitrilium salts has also been postulated42 in the Schmidt reaction and in some Beckmann rearrangements when concentrated sulfuric acid is employed. Hill43 has demonstrated recently that some Beckmann rearrangements carried out in a concentrated sulfuric acid medium are Ritter-type reactions in which the nitrile formed in situ from the oxime combines with a carbonium ion to yield a nitrilium salt, which, when diluted with water, leads to the N-alkylamide. 

Iminium halides are intermediates in the hydrolysis of nitriles and in a variety of chemical reactions. For example, in the Ritter reaction addition of a nitrile or hydrogen cyanide to a carbonium ion occurs, leading to the intermediate formation of a nitrilium salt. Nitrilium salt intermediates have also been postulated in the Schmidt reaction and in the Beckmann rearrangement, provided the latter was performed in concentrated sulfuric acid. However, since we are predominantly concerned with imidoyl halides, these reactions are not discussed in this monograph. 

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