Proline imidazolidinones and enamines in Hajos–Wiechert and Wieland–Miescher ketone synthesis

Readily available aromatic prolinamides obtained from the acid chloride of proline hydrochloride and anilines induce large enantiomeric excesses in intramolecular aldol condensations. Imidazolidinones derived from the reaction of the catalyst and enamines have been found as intermediates in these reactions.