Palladium-Catalyzed Asymmetric Trifluoromethylated Allylic Alkylation of N-Substituted Glycine Ethyl Esters with α-(Trifluoromethyl)alkenyl Acetates

An efficient strategy for asymmetric trifluoromethylated allylic alkylation of easily available N-substituted glycine ethyl esters with α-(trifluoromethyl)alkenyl acetates has been developed. Catalyzed by a [Pd(C₃H₅)Cl]₂/(R)-BINAP, various trifluoromethyl-containing N-substituted glycine ethyl ester derivatives are afforded with good yields and excellent enantioselectivities. The product can be readily converted into diverse fluoro-substituted species, which shows the practicability of this method.     

Ruthenium-Catalyzed Direct Reductive Amination of Carbonyl Compounds for the Synthesis of Amines: An Overview

Reductive amination is a valuable method for amine synthesis that has been the topic of a century‘s worth of in-depth study in both academia and industry. Amines and their derivatives serve as incredibly adaptable building blocks for a broad array of organic substrates and are significant precursors for a myriad of advanced chemicals, physiologically active compounds, agrochemicals, biomolecules, pharmaceuticals, and polymers. The creation of innovative catalytic processes for the long-term and selective synthesis of amines from readily accessible and environmentally benign reagents remains a top priority in chemical research. Both heterogeneous and homogeneous catalysts have been designed with success to enable these reactions to explore new amines. Ruthenium catalysts are employed in reductive amination owing to their stability, selectivity, versatility, low toxicity, and high efficiency. This review comprehensively overviews the Ru-catalyzed reductive amination processes and includes the literature from 2009 to 2022.     

New Trends in Asymmetric Phase Transfer Catalysis

Phase Transfer Catalysis (PTC) is a powerful tool to perform reactions in a practical fashion, both in laboratory and industrial scale. Significant cost savings and major process improvements can be achieved in reactions performed under PTC conditions. In the last few years remarkable results in stereoselective reactions were achieved using chiral, non-racemic quaternary ammonium salts. Moreover, the use of bulky, chiral phosphate anions paired with achiral cations to generate lipophilic ion pairs allowed to design new avenues for the stereoselective construction of important building blocks. Hydrogen bond interactions were also shown to provide new pathways for asymmetric nucleophilic substitutions using insoluble reagents under PTC conditions. This Review will focus on recent advances in developing practical synthetic routes to construct molecules in a stereoselective fashion under PTC conditions.     

Diarylprolinol as an Effective Organocatalyst in Asymmetric Cross-Aldol Reactions of Two Different Aldehydes

The aldol reaction is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Asymmetric direct cross-aldol reaction of two different aldehydes has been regarded as a difficult reaction because of the side reactions such as self-aldol reaction and over reaction. We found that trifluoromethyl-substituted diarylprolinol, α,α-bis[3,5-bis(trifluoromethyl)phenyl]-2-pyrrolidinemethanol ( 1 ), is an effective organocatalyst that promotes several cross-aldol reactions of aldehydes with excellent diastereo- and enantioselectivities. Acetaldehyde can be employed as a suitable nucleophilic aldehyde. Successful electrophilic aldehydes are ethyl glyoxylate, chloroacetaldehyde, dichloroacetaldehyde, chloral, α-alkyl-α-oxo aldehyde, trifluoroacetaldehyde, glyoxal, alkenyl aldehyde, alkynyl aldehyde, and formaldehyde. Some of the aldehydes are commercially available as a polymer solution, an aqueous solution, or in the hydrated form. They can be used directly in the asymmetric aldol reaction as a commercially available form, which is a synthetic advantage. Given that the obtained aldol products possess several functional groups along with a formyl moiety, they are synthetically useful chiral building blocks.     

Cover Picture: Axis-Unfixed Biphenylphosphine-Oxazoline Ligands: Design and Applications in Asymmetric Catalytic Reactions (Chem. Rec. 10/2023)

The design and synthesis of chiral ligands plays an important role in asymmetric catalytic reactions. Over the past decades, various types of chiral phosphine-oxazolines (PHOX ligands) have been developed and have greatly advanced the field of asymmetric catalysis. Novel chiral PHOX ligand with an axis-unfixed biphenyl backbone, developed by our group, have shown interesting coordination behavior and excellent chiral inducing ability in various transition-metal-catalyzed asymmetric reactions. This personal account focuses on our developed axis-unfixed biphenylphosphine-oxazoline ligand (BiphPHOX), including an overview of its design and applications, which will provide inspiration for the exploration of novel ligands and related reactions.     

基于曲线问题情境的信息化教学尝试*——以“沉淀溶解平衡”为例

基于高中生对实验曲线理解困难的现状,为挖掘实验曲线的教学价值,以沉淀溶解平衡为例,结合课堂演示实验和教学软件,设计了“宏观微观符号曲线”多重表征教学为一体的实验探究课。根据沉淀溶解平衡实验证据,绘制实验曲线,构建微观模型和图像,从而培养学生的证据收集与应用意识,提高学生对曲线的分析和理解能力,领会各种变化曲线的来源。在曲线理解的基础上建立“溶解平衡转化”思维模型,以此为开展“曲线融入式”的问题引导型实验教学提供参考案例。     

CBS还原合成手性1-苯乙醇实验设计*

将学科热点之一催化不对称合成策略引入实验教学中,通过CBS还原制备手性醇。实验以苯乙酮为原料,还原得到粗产物手性1-苯乙醇,经制备色谱仪分离提纯,气相色谱和自动旋光仪表征产物的光学性质。实验为综合型有机化学实验,通过此实验,学生在掌握手性醇合成原理与方法的同时,进一步学习手套箱、气相色谱、制备色谱仪、自动旋光仪等新技术,以提升学生综合科研素质。     

Janus 粒子在环境检测领域中的应用

Janus 粒子,也称为阴阳结构粒子或两面性非对称粒子,是指表面上具有两种或两种以上不同化学组成或性质的不对称粒子。目前,Janus 粒子因其独特的结构和功能已经逐渐成为生物医药、催化、材料以及防污等领域中的新型功能材料。在环境检测领域,Janus材料亦因其特殊的光学、磁学及电学性能,为提高检测灵敏度、选择性和稳定性等提供了新的研究方向。基于此,本文主要讨论了Janus材料在环境检测方面的特点、优势和相关应用。最后,本文基于本课题组的研究经验以及工作中所面临的问题,对本领域的发展和未来的研究方向提出了展望,以期对本领域的未来发展提供指导。     

Enantioselective Total Synthesis of (+)-Nordasycarpidone, (+)-Dasycarpidone,and (+)-Uleine

The structure of uleine type alkaloids is characterized by the presence of a bridged tetracyclic hexahydro-1H-1,5-methanoazocino[4,3-b]indole ring system 1 . Various strategies have been developed to access this polycyclic structural motif. We report herein a one-step conversion of appropriately functionalized 1,3,4-trisubstituted cyclopent-1-ene to 1 by way of an integrated oxidation/reduction/cyclization (iORC) process. This domino sequence, initiated by oxidative cleavage of cyclopentene ring, generated subsequently a cyclohexenone, an indole and a 1,3-bridged piperidine ring through formation of one C−C and two C−N bonds. Compound 1 is subsequently converted to nordasycarpidone, dasycarpidone and uleine. The chirality of the molecule was introduced by enzymatic desymmetrization of commercially available meso cis-3,5-diacetoxy-1-cyclopentene.     

A Bifunctional B,N-Based Asymmetric Catalytic Nitrostyrene-Michael Addition Acting through a 10-Membered Ring Cyclic Transition State

The B,N-bifunctional catalyst homoboroproline has been applied to a catalytic asymmetric nitroalkene-Michael addition to β-nitrostyrene analogues, showing broad substrate tolerance, high conversions and moderate to good asymmetric induction. The ability of homoboroproline to act as an efficient catalyst based on enamine-formation of the secondary amine, coupled with intramolecular Lewis-acid chelation of the nitro function, in a non-FLP manner, to effect efficient and enantioselective catalysis via a proposed large 10-membered ring transition state is remarkable and reinforced by theoretical calculations.