Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
作者:Marek Stankevič
DOI:10.1039/c4ob02440k
日期:——
Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
A Practical Electrophilic Nitrogen Source for the Synthesis of Chiral Primary Amines by Copper-Catalyzed Hydroamination
作者:Sheng Guo、Jeffrey C. Yang、Stephen L. Buchwald
DOI:10.1021/jacs.8b10564
日期:2018.11.21
and practical method for the catalytic installation of the amino group across alkenes and alkynes has long been recognized as a significant challenge in synthetic chemistry. As the direct hydroamination of olefins using ammonia requires harsh conditions, the development of suitable electrophilic aminating reagents for formal hydroamination methods is of importance. Herein, we describe the use of 1
Synthesis of <i>N</i>-alkylated lipopeptides and their application as organocatalysts in asymmetric Michael addition in aqueous environments
作者:José A. C. Delgado、Fidel E. M. Vicente、Alexander F. de la Torre、Vitor A. Fernandes、Arlene G. Corrêa、Márcio W. Paixão
DOI:10.1039/d1nj01112j
日期:——
through an isocyanide-based multicomponent reaction. Various structural motifs were tunably introduced on the catalyst backbone with the aim of incorporating amphiphilic features. Consequently, they have further been evaluated in the 1,4-addition of aldehydes to trans-β-nitrostyrene having water as the sole solvent. Under sustainable reactionconditions, Michael adducts were obtained in excellent yields
A Simple Diastereoselective Synthesis of Chiral Nonracemic Aliphatic Amines
作者:G. V. Grishina、E. R. Luk’yanenko、A. A. Borisenko
DOI:10.1007/s11178-005-0248-1
日期:2005.6
An efficient procedure has been developed for the diastereoselective synthesis of chiral aliphatic amines (diastereoisomeric excess >96%) from (1S)-N-(1-methylethylidene)-1-phenylethylamine, i.e., Schiff base derived from the simplest ketone (acetone) and (1S)-1-phenylethylamine. The procedure includes successive lithiation, alkylation, and reduction and is characterized by high regioselectivity in the formation of alkylated syn-Z-imines. Hydride reduction of the prochiral C=N bond in the latter gives mainly optically active aliphatic amines with R configuration. All reactions are performed as a one-pot process without isolation of intermediate products.
开发了一种有效的方法,用于从 (1S)-N-(1-甲基亚乙基)-1-苯乙胺(即源自最简单的酮(丙酮)的席夫碱)非对映选择性合成手性脂肪胺(非对映异构体过量 >96%)和(1S)-1-苯乙胺。该过程包括连续的锂化、烷基化和还原,其特点是在烷基化顺式-Z-亚胺的形成中具有高区域选择性。后者的前手性 C=N 键的氢化物还原主要产生具有 R 构型的光学活性脂肪胺。所有反应均以一锅法进行,无需分离中间产物。
Preparation of axially chiral quinolinium salts related to NAD+ models: new investigations of these biomimetic models as ‘chiral amide-transferring agents’
The general purpose of this work is to investigate the potential of biomimetic NAD(+) models as 'nucleophile-transferring agents' with the ultimate motivation to develop new synthetic tools. This first report focuses on the preparation of an axially chiral quinolinium salt 8. A preliminary investigation of these NAD(+) analogues as 'chiral amide-transferring agents' is reported herein. The synthesis of the desired quinolinium salt 8 was first attempted via a Friedlander approach. Given the poor reproducibility of this first synthetic route, a second strategy making use of an intramolecular nickel-catalyzed coupling was developed with success, furnishing the quinolinium salt 8 in 12% overall yield. The potential of the quinolinium salt 8 as a 'chiral amide-transferring agent' was then investigated. Regioselective 1,4-addition of benzylamine and piperidine produced, respectively, adducts 18a and 18b with high diastereoselectivity (de >95%). The resulting 'chiral masked-amide' 18b was reacted with various activated aryl esters affording the corresponding atropisomeric amide 20 with modest atropenantioselectivity (ee = 2-20%). (C) 2004 Elsevier Ltd. All rights reserved.