Non-biaryl atropisomers derived from carbohydrates. Part 2. Atropisomeric behavior of monocyclic and bicyclic imidazolidine-2-ones and 2- thiones

Article abstract of DOI:10.1016/S0040-4020(99)00110-6

High-yielding syntheses of bicyclic imidazolidine-2-ones and 2-thiones bearing an ortho-substituted aromatic ring have been described. Their atropisomeric behavior has been studied in depth taking into account the effects of substituents in the ortho position, the length of the exocyclic C=X bond, and the presence of substituents at C-5 in the heterocyclic ring. The barriers to rotation were independently estimated by dynamic NMR spectroscopy and molecular mechanics.