Synthesis of chiral pentacyclo-undecane ligands and their use in the enantioselective alkylation of benzaldehyde with diethylzinc
摘要:
The synthesis of a new class of chiral pentacycloundecane cage annulated bidentate ligands is reported. This class of ligands can be used in many reactions that are catalysed by amino alcohol ligands. The ability of the chiral ligands to asymmetrically catalyse the reaction between diethylzinc and benzaldehyde was investigated. The cage annulated bidentate ligands have C, symmetry and showed poor to good enantioselectivity with high yields compared to previous systems reported using other amino alcohol ligands. An important conclusion from the results is that both ligands should be involved in the mechanism as the bidentate ligands gives much improved enantioselectivity when compared with a single chiral source molecule. This system could be utilised as a versatile probe for examining the reaction mechanism. (C) 2004 Elsevier Ltd. All rights reserved.
Palladium-Catalyzed Double and Single Carbonylations of<i>β</i>-Amino Alcohols. Selective Synthesis of Morpholine-2,3-diones and Oxazolidin-2-ones and Applications for Synthesis of<i>α</i>-Oxo Carboxylic Acids
Catalytic crossdoublecarbonylation of secondary amines and alcohols proceeds in the presence of [PdCl2(MeCN)2] and CuI under carbon monoxide (80 atm) and oxygen (5 atm). Catalytic intramolecular doublecarbonylation of β-amino alcohols gives morpholine-2,3-diones, which are excellent protecting compounds of amino alcohols and important precursors for biologically active nitrogen compounds. In contrast
仲胺和醇的催化交叉双羰基化在一氧化碳 (80 atm) 和氧气 (5 atm) 下在 [PdCl2(MeCN)2] 和 CuI 的存在下进行。β-氨基醇的催化分子内双羰基化得到吗啉-2,3-二酮,它是氨基醇的极好保护化合物和生物活性氮化合物的重要前体。相比之下,在一氧化碳和氧气 (1.0 atm) 的混合物 (1:1) 下,β-氨基醇的催化单羰基化进行选择性地得到恶唑烷-2-酮。该反应可以通过假设一种机制来解释,该机制包括(羟乙基)氨基羰基配体的羟基对氨基甲酰基钯 (II) 配合物的 CO 配体的分子内亲核攻击,然后还原消除得到吗啉-2,3-二酮。相反,羟基对氨基甲酰基的直接亲核攻击提供了恶唑烷-2-酮。作为双音和单音的常用中间体...
Enantioselective syntheses of α-phenylalkanamines via intermediate addition of Grignard reagents to chiral hydrazones derived from (R)-(−)-2-aminobutan-1-ol
作者:Patricia Bataille、Michel Paterne、Eric Brown
DOI:10.1016/s0957-4166(98)00217-1
日期:1998.6
The hydrazine (R)-(−)-28 was obtained in four steps from 2-aminobutan-1-ol (R)-(−)-11, and reacted with benzaldehyde to give the hydrazone (R)-(−)-29. Nucleophilic addition of various alkyl Grignardreagents to the latter yielded the corresponding trisubstituted hydrazines (R,R)-30a–g in 70–89% yields and having d.e.s=100% (1H and 13C NMR). Catalytic hydrogenolysis of these hydrazines afforded the
从2-氨基丁-1-醇(R)-(-)- 11通过四个步骤获得肼(R)-(-)- 28,并与苯甲醛反应得到the(R)-(-)-。29。向后者亲核添加各种烷基格氏试剂可得到相应的三取代肼(R,R)-30a - g,产率为70-89%,des = 100%(1 H和13 C NMR)。这些肼的催化氢解反应提供了相应的(R)-(+)-α-苯基链烷胺(R)-(+)- 31a – g ee = 90–92%(手性GPC)。
Diastereoselective Synthesis of Chiral Amidophosphonates by 1,5-Asymmetric Induction
We have investigated two simple diastereoselective syntheses of substituted β-amidophosphonates. The first one involved a Michael addition to α,β-unsaturated amides 6 and 8a−d, derived fromchiral amino alcohols, and permitted the preparation of alkyl-substituted derivatives 7 and 9a−d with high diastereoselectivities (up to 95%) with the aid of a 1,5-asymmetric induction. The second one, involving
Dual SNAr reaction in activated ortho-halonitrobenzene: direct synthesis of substituted 1,2,3,4-tetrahydroquinoxalines, 2,3-dihydro-1,4-benzoxazines, and 1,4-benzodioxines
作者:Mahesh S. Deshmukh、Biswajit Das、Nidhi Jain
DOI:10.1039/c3ra44386h
日期:——
An unprecedented one-pot synthesis of substituted 1,2,3,4-tetrahydroquinoxalines, 2,3-dihydro-1,4-benzoxazines, and 1,4-benzodioxines from activated ortho-halonitrobenzenes has been accomplished by dual nucleophilic aromatic substitution (SNAr) of halogen followed by substitution of the nitro group by secondary diamines, secondary amino alcohols, and diols respectively.
N-Arylacyl- und N-Arylalkyl-Derivate von 2-Amino-1-butanol mit zwei Chiralitätszentren
作者:Marian Eckstein、Marek Cegła、Leonard Gajewczyk
DOI:10.1002/ardp.19863190711
日期:——
Die Synthese aller optisch isomeren 2‐N‐(2‐Phenylbutyryl)‐amino‐1‐butanole 1a–d und 2‐N‐Methyl‐N‐(2‐phenylbutyryl)‐amino‐1‐butanole 2a–d wird beschrieben. Die Reduktion der Amide führt zu den entsprechenden Aminen 3a–d und 4a–d. Jede dieser Verbindungen enthält zweiChiralitätszentren, deren absolute Konfiguration bestimmt wird.