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.
value of the methodology described is demonstrated by providing (a) a direct route for the asymmetricsynthesis of differently substituted 1,2-diamines and (b) a new asymmetricsynthesis of gamma-amino alpha,beta-unsaturated esters through a catalytic, highly enantioselective formal addition of functionalized alkenyl groups to azomethines. Finally, a preferred TS that nicely fits the observed enantioselectivity
Enantioselective aza-Henry reaction of t-Boc protected imines and nitroalkanes with bifunctional squaramide organocatalysts
作者:Dilşad Susam、Cihangir Tanyeli
DOI:10.1039/c6nj04078k
日期:——
An organocatalytic asymmetric aza-Henry reaction of t-Boc protected imines with nitroalkanes has been established by chiral acid–base type bifunctional Cinchona alkaloid/squaramideorganocatalysts. The cooperation of a quinine motif as a base and sterically encumbered squaramide (H-bond donor) enabled mostly complete conversion of a range of reactants into the corresponding aza-Henry products at room
t - Boc保护的亚胺与硝基烷烃的有机催化不对称aza-Henry反应是通过手性酸碱型双功能金鸡纳生物碱/方酰胺有机催化剂建立的。奎宁基序作为碱和空间受限的方酰胺(氢键供体)的配合,可以在室温下以良好的选择性将一系列反应物完全转化为相应的aza-Henry产品(选择性高达91%ee,10 mol)催化剂负载百分比)。
Catalytic Asymmetric Nitro-Mannich Reactions with a Yb/K Heterobimetallic Catalyst
A catalyticasymmetric nitro-Mannich (aza-Henry) reaction with rareearth metal/alkali metal heterobimetallic catalysts is described. A Yb/K heterobimetallic catalyst assembled by an amide-based ligand promoted the asymmetric nitro-Mannich reaction to afford enantioenriched anti-b-nitroamines in up to 86% ee. Facile reduction of the nitro functionality allowed for efficient access to optically active
描述了与稀土金属/碱金属异双金属催化剂的催化不对称硝基-曼尼希 (氮杂-亨利) 反应。由基于酰胺的配体组装的 Yb/K 杂双金属催化剂促进了不对称硝基-曼尼希反应,以提供高达 86% ee 的对映体富集的抗 b-硝基胺。硝基官能团的轻松还原允许有效获取光学活性 1,2-二胺。
Catalytic Enantioselective Aza-Henry Reaction with Broad Substrate Scope
ammonium chlorides to provide the corresponding aza-Henry adducts in good yields and very high selectivities. It represents the first general enantioselectiveaza-Henry method for azomethines derived from enolizable aldehydes, giving rise to enantiomeric excesses above 94%. In addition, the reactions with nitroethane afforded high diastereo- and enantioselectivities (syn:anti up to 95:5; up to 98% ee for syn)