Bending Enamine Patterns of Stabilized Pentalenes into "Polymethine Ylides"

We report the synthesis and structural study of 2-substituted 1,3-bis(dimethylamino)pentalenes. The two electrons donating substituents shift the formally anti-aromatic pattern toward more suitable polarized structures. A subtle steric trade-off can result either in planar cyclopentadienyl vinamidiniums or in distorted structures featuring a pyramidalized ylidic carbon adjacent to a stabilized π-conjugated iminium (polymethine). This latter pattern mimics a postulated activated distorted geometry for key Breslow intermediates in the active site of thiamine-dependent enzymes. It highlights how the energetic drive to avoid anti-aromaticity can be used to access models for unconventional distorted conformations of organic molecules.

Références

Titre
Bending Enamine Patterns of Stabilized Pentalenes into "Polymethine Ylides"
Type de publication
Article de revue
Année de publication
2023
Revue
Organic Letters
Volume
25
Pagination
560–564
ISSN
1523-7060
Soumis le 3 février 2023