Enantioselective Aza-Henry Reaction with an <i>N</i>-Sulfinyl Urea Organocatalyst
作者:MaryAnn T. Robak、Monica Trincado、Jonathan A. Ellman
DOI:10.1021/ja075653v
日期:2007.12.1
simultaneously acidify the urea and provide asymmetric induction in hydrogen-bond-catalyzed reactions. The utility of this new catalyst structure is demonstrated by the high selectivity provided in the aza-Henryreaction not only for aromatic N-Boc imine substrates but also for aliphatic imines for which enantioselective H-bonding catalysis has not previously been demonstrated.
catalytic enantio- and diastereoselective nitro-Mannichreaction of α-amido sulfones in the mixed solvent of toluene/H2O has been realized using a phase-transfer catalyst (PTC) derived from cinchona alkaloids and N-benzotriazole. It performed well over a wide range of substrates to give the desired products in good yields (up to 94%) with excellent enantioselectivities (up to 99% ee) and diastereoselectivities
使用衍生自金鸡纳生物碱和N-苯并三唑的相转移催化剂(PTC)实现了α-酰胺基砜在甲苯/ H 2 O混合溶剂中的催化对映体和非对映体的硝基曼尼希反应。它在各种底物上均表现良好,以高收率(最高94%)提供所需的产品,并具有出色的对映选择性(最高99%ee)和非对映选择性(最高99:1)。
Asymmetric Phase-Transfer Catalysts Bearing Multiple Hydrogen-Bonding Donors: Highly Efficient Catalysts for Enantio- and Diastereoselective Nitro-Mannich Reaction of Amidosulfones
Bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors have rarely been explored. The first quaternary ammonium type of these catalysts derived from cinchona alkaloids were readily prepared and found to be highly efficient catalysts for asymmetric nitro-Mannichreactions of amidosulfones. Compared with previous reports, very broad substrate generality was observed
New quaternary ammonium types of bifunctional asymmetric phase-transfercatalysts bearing multiple hydrogen-bonding donors derived from α-amino acids were readily prepared and found to be highly efficient in the asymmetric nitro-Mannich reactions of amidosulfones. Very broad substrate generality was observed, and the products were achieved in high enantio-/diastereoselectivities (90–>99.9% ee, 90 : 10