The Mannich Reaction of Malonates with Simple Imines Catalyzed by Bifunctional Cinchona Alkaloids: Enantioselective Synthesis of β-Amino Acids
作者:Jun Song、Yi Wang、Li Deng
DOI:10.1021/ja060716f
日期:2006.5.1
efficient, direct asymmetric Mannichreactions with malonates and N-Boc aryl and alkyl imines by cooperative hydrogen-bonding catalysis with a cinchona alkaloid bearing a thiourea functionality. We have also extended the scope of this reaction to beta-ketoesters. The synthetic value of this new reaction is demonstrated in the establishment of a convergent enantioselective route toward the biologically
A Bench-Stable Homodinuclear Ni<sub>2</sub>−Schiff Base Complex for Catalytic Asymmetric Synthesis of α-Tetrasubstituted <i>anti</i>-α,β-Diamino Acid Surrogates
Catalyticasymmetric direct Mannich-type reactions of α-substituted nitroacetates using a new bench-stable homodinuclear Ni2−Schiff base 1b complex are described. The Ni2−1b complex gave Mannich products, precursors for anti-α,β-diamino acids with an α-tetrasubstituted carbon stereocenter, in >99−91% ee. The Ni2−1b complex was also applicable to direct Mannich-type reactions of malonates and β-keto
Asymmetric Mannich Reaction of Dicarbonyl Compounds with α-Amido Sulfones Catalyzed by Cinchona Alkaloids and Synthesis of Chiral Dihydropyrimidones
作者:Sha Lou、Peng Dai、Scott E. Schaus
DOI:10.1021/jo701777g
日期:2007.12.1
The highly enantioselective cinchona alkaloid-catalyzed Mannich reaction of dicarbonyl compounds with α-amidosulfones as acyl imine precursors is described. The reaction requires 10 mol % of the cinchona alkaloid catalyst, which serves as a general base to generate acyl imines in situ, and aqueous Na2CO3 to maintain the concentration of free alkaloid catalyst. The reaction products are obtained in
描述了二羰基化合物与α-酰胺基砜作为酰基亚胺前体的高度对映选择性金鸡纳生物碱催化的曼尼希反应。该反应需要10 mol%的金鸡纳生物碱催化剂和Na 2 CO 3水溶液,该催化剂可作为一般的碱在现场生成酰基亚胺。保持游离生物碱催化剂的浓度。以高收率和高对映选择性以及从1∶1至> 95∶5的非对映选择性获得反应产物。辛可宁催化的反应提供了高度实用的结构单元的实际途径,该结构单元已用于手性二氢嘧啶酮的合成,手性二氢嘧啶酮是一类具有多种生物活性的化合物。二氢嘧啶酮修饰包括使用H-Cube流动氢化器和Rh(II)介导的1,3-偶极环加成反应对烯酰胺部分进行高度非对映选择性氢化,以提供高度官能化的复杂杂环。
Solvent-Dependent Enantiodivergent Mannich-Type Reaction: Utilizing a Conformationally Flexible Guanidine/Bisthiourea Organocatalyst
Flex control: Malonate and tert‐butoxycarbonyl (Boc)‐protected imines react in the presence of the flexible catalyst 1 to furnish the S or the R adduct depending upon the solvent used. Kinetic analyses in this enantiodivergent organocatalysis show that enthalpy–entropy compensation explains this behavior.
Sequential enantiodivergent organocatalysis: reversibility in enantioswitching controlled by a conformationally flexible guanidine/bisthiourea organocatalyst
Here we describe our studies on solvent-dependentenantiodivergentMannich-typereactionsutilizingconformationallyflexibleguanidine/bisthioureaorganocatalyst (S,S)-1. Our mechanistic investigations revealed that the stereo-determining steps in both the (R)- and (S)-selective Mannich-typereactions are governed by the cooperative effect of guanidine and thiourea in the inherently monomeric structure