C2-symmetric proline-derived tetraamine as highly effective catalyst for direct asymmetric Michael addition of ketones to chalcones.Org Biomol Chem. 2012 May 14; 10(18):3721-9.OB
A C(2)-symmetric tetraamine catalyst was developed for the asymmetric Michael addition of ketones to chalcones. The corresponding adducts 1,5-dicarbonyl compounds were obtained in good chemical yields with high levels of diastereo- and enantioselectivities (up to >99 : 1 dr and 93% ee) under mild conditions. By studying the ESI-MS of the intermediates, a proposed mechanism was disclosed.