A new family of bifunctional organocatalysts with conformationally rigid H-bond donors was successfully synthesized and applied to the aqueous phase Michael reactions of cyclohexanone with nitroolefins. The corresponding products were obtained with high enantioselectivities (up to 99% ee) and diastereoselectivies (up to 99/1 dr) in the presence of a slight excess of Michael donors in brine at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.
Novel aminoimidazole derived proline organocatalysts for aldol reactions
作者:Gongkun Tang、Ümit Gün、Hans-Josef Altenbach
DOI:10.1016/j.tet.2012.09.071
日期:2012.12
highly efficient organocatalysts for aldol reactions when an appropriate acid was added to control and activate the acceptor carbonyl group. Under optimized reaction conditions, high yields (over 80%) and high selectivities (ee 98%, de 98/2) were obtained in intermolecular aldol reaction even with only 1 equiv of ketone. Likewise, these systems also can catalyze intramolecular aldol reactions with good results