By exploiting the thermal instability about the Ar-CO axis at high temperature, atropisomeric amides can be dynamically resolved to provide material with up to 96.5 % ee in 70-80 % overall yield from racemic starting material. The amides are coupled with a diamine resolving agent and equilibrated to single diastereoisomers. Hydrolysis returns enantiomerically enriched amide (see reaction scheme).
Dynamic resolution of atropisomeric amides using proline-derived imidazolines and ephedrine-derived oxazolidines
some chiral diamines and amino alcohols leads, via a dynamic resolution process, to single atropisomers of tertiary amides bearing chiralimidazolidines or oxazolidines. Hydrolysis of the new heterocycle competes a dynamic thermodynamic resolution of the starting aldehyde, and rapid reduction allows the isolation of atropisomeric amides bearing 2-hydroxymethyl substituents in enantiomerically enriched