Abstract An efficient, highly stereoconservative synthesis has been developed for the preparation of aniline derived 1-arylpyrrole-2-carboxamide atropisomers using diphenylphosphoryl azide (DPPA). The classical azide synthesis, involving reaction with active acylating agents prepared from axially chiral benzoic acid derivatives, showed significant racemization caused by intramolecular tricyclic isoimidium salt formation. In order to avoid the ring closure reaction, the azide synthesis was carried out with DPPA in a stereoconservative manner, and Curtius rearrangement followed by hydrolysis resulted in enantiopure products. The application of the novel racemisation-free synthetic method of axially chiral anilines from atropisomeric benzoic acid derivatives is demonstrated by the preparation of secondary as well as tertiary amines containing 2-(2-substituted-1H-pyrrole-1-yl)aniline type diamines.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry