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Cyclisations par l'intermédiaire de fonctions phénylthioet phénoxy‐carbamoyle. II. Formation d'anhydrides azasucciniques et de leurs produits de polycondensation. Intervention du cation carbamoyle‐pyridinium
Author(s) -
Baudet P.,
Otten Cl.,
Rao D.
Publication year - 1970
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19700530428
Subject(s) - chemistry , steric effects , pyridine , medicinal chemistry , pyridinium , glycine , catalysis , polymer chemistry , stereochemistry , organic chemistry , amino acid , biochemistry
The N‐( p ‐nitrophenoxy‐carbonyl) derivatives of glycine, DL ‐alanine and DL ‐leucine are transformed by the action of pyridine into azasuccinic, 3‐methyl‐2‐azasuccinic and 3‐isobutyl‐2‐azasuccinic anhydride, respectively. These cyclisations occur probably via the intermediate N‐carbamoyl‐pyridinium cation, the rate of cyclisation seems to depend on the concentration of the intermediate in the form of the dipolar ion, i.e. the ionised carboxyl is necessary for the reaction. In γ‐collidine the cyclisation occurs very slowly; this is attributed to the slowness due to steric hindrance of the production of N‐carbamoyl‐γ‐collidinium cation and its instability. The azasuccinic anhydrides mentioned polycondense, yielding the corresponding polyglycine, poly‐ DL ‐alanine and poly‐ DL ‐leucine. This reaction too is catalysed by pyridine; it can also be effected by γ‐collidine, but the efficacity of the latter in comparison with pyridine is even less than in the catalysis of the cyclisation described above. N‐( p ‐nitrophenoxy‐carbonyl)‐glycine reacts with lysozyme in the presence of pyridine; several glycine residues are introduced into the enzyme molecule, the product being insoluble and poorly active.