Review
Chemistry, Applied
Seoung-Mi Choi, Ju Hyun Kim
Summary: This review summarizes the progress made in the synthesis of 2H-pyrroles since 2000, including methods such as dearomatization of 1H-pyrrole, oxidation of pyrrolines or pyrrolidines, ring construction via catalytic cycloaddition, and rearrangement of 3H-pyrroles.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Review
Chemistry, Multidisciplinary
Fujie Tanaka
Summary: This article discusses catalysts and catalyst systems that use amino acids, primary, secondary, and/or tertiary amines as key catalytic functional groups to accelerate chemical transformations. It also explores strategies and methods that utilize amine derivatives as catalysts. The understanding of dynamics and kinetic controls in amine-catalyzed reactions has enabled the synthesis of complex molecules in stereocontrolled manners.
Article
Chemistry, Multidisciplinary
Rosa Lopez, Claudio Palomo
Summary: N,N-Diacylaminals are flexible molecular scaffolds commonly used as amide surrogates in peptidomimetics. Recently, their singularity as an N-acyl imine equivalent and hydrogen-bond donor has led to new synthetic opportunities, particularly in the field of asymmetric catalysis. This concept article highlights the diverse synthetic potential of N,N-Diacylaminals and provides the necessary elements for further developments.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Review
Chemistry, Organic
Wei Wen, Qi-Xiang Guo
Summary: This article summarizes the recent advances in the application of chiral aldehyde catalysis in asymmetric reactions and prospects its future development.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Multidisciplinary
Roberto del Rio-Rodriguez, Matthew T. Westwood, Marina Sicignano, Martin Juhl, Jose A. Fernandez-Salas, Jose Aleman, Andrew D. Smith
Summary: This study combines the photocatalytic generation of alpha-amino radicals with chiral isothiourea derived alpha,beta-unsaturated acyl ammonium intermediates. The reaction proceeds via a [3+2] radical-polar crossover mechanism to generate gamma-lactams with good yields and enantioselectivities. The enantioselective radical conjugate addition was carried out under batch and flow conditions.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Apoorva Malik, Pragati R. Sharma, Rakesh K. Sharma
Summary: We report a class of quaternary ammonium Cinchona-functionalized crown ether-strapped calix[4]-arene phase-transfer catalysts for the efficient enantioselective alpha-alkylation of glycine imines. The catalyst exhibits excellent catalytic performance at 0.1 mol % catalytic loading, affording the desired alpha-alkylated glycinates with 98% yield and 99.9% ee. The catalyst could be recovered and recycled up to 30 test cycles without a significant drop in activity.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Paul Zebrowski, Uwe Monkowius, Mario Waser
Summary: We report a two-step approach for the enantioselective synthesis of novel chiral δ-lactams. The protocol involves an asymmetric α-allylation of activated aryl esters followed by an acid-mediated lactam formation. The method provides highly enantioselective and reasonably high-yielding products, which can be further utilized via transformations of the exocyclic double bond.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Qingqing Luo, Zhou Tian, Jie Tang, Jie Wang, Yin Tian, Cheng Peng, Gu Zhan, Bo Han
Summary: The study focuses on the design of bifunctional 4-pyrrolidinopyridines as Lewis base catalysts, which exhibited excellent efficiency and stereoselectivity in asymmetric cycloaddition reactions. The research provides strong support for the construction of chiral spiropyrazolone derivatives.
Article
Chemistry, Organic
Feng Jiang, Tengfei Meng, Ying Zhou, Zhenying Xiong, Yupei Zhao, Wengang Guo
Summary: We report an enantio- and diastereodivergent synthesis of enantioenriched fluorenes with broad substrate scope and high enantioselectivity (up to 99% ee) under low catalyst loading (0.1 mol %). The success of this method lies in the pseudo-diastereodivergent desymmetrization of stereoisomers of meso-epoxides enabled by the same organocatalyst. Furthermore, some of the chiral fluorenes obtained exhibit high fluorescence quantum yields (up to 76.6%), as evidenced by photophysical properties studies.
Article
Chemistry, Organic
Gen-Fa Wen, Rui Zhang, Chu-Yu Zhang, Chao-Shan Da
Summary: This study compares and explores the catalytic efficiencies of structurally similar alpha- and beta-amino acids in an asymmetric aldol transformation. The results show that both types of amino acids achieve high catalytic efficiencies under different optimal conditions, and in some cases, the beta-amino acid even exhibits higher enantioselectivity than the alpha-amino acid.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Applied
Ken Okuno, Bun Chan, Seiji Shirakawa
Summary: Catalytic kinetic resolution is a reliable method for enantioselective synthesis of chiral molecules. However, it is challenging to perform kinetic resolution on racemic compounds with similar substituents at a chiral center. In this study, a kinetic resolution of a-allyl-a-propargyl carboxylic acids was achieved using a chiral bifunctional sulfide catalyst. The utility of the resulting optically active compounds was also demonstrated.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Jia-Bin Pan, Zhi-Chun Yang, Xuan-Ge Zhang, Mao-Lin Li, Qi-Lin Zhou
Summary: Here, we present a method for enantioselective phosphoric acid catalyzed amination of ketenes generated from α-aryl-α-diazoketones. Mechanistic studies elucidated the reaction pathway and explained how the catalyst expedited the transformation and controlled the enantioselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Avene C. Colgan, Rupert S. J. Proctor, David C. Gibson, Padon Chuentragool, Antti S. K. Lahdenpera, Kristaps Ermanis, Robert J. Phipps
Summary: This study reports a significant advancement in the catalytic enantioselective Minisci reaction, allowing the use of α-hydroxy radical coupling partners to obtain valuable enantioenriched secondary alcohol products. The approach is highly regioselective as well as highly enantioselective.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Marina Perez-Palau, Nil Sanosa, Pedro Romea, Felix Urpi, Rosa Lopez, Enrique Gomez-Bengoa, Merce Font-Bardia
Summary: A new stereoselective alkylation method has been developed using titanium(IV) enolates of chiral N-acyl oxazolidinones with tert-butyl peresters from Ca-branched aliphatic carboxylic acids. The reaction proceeds through the decarboxylation of peresters and formation of alkyl radicals, resulting in alkylated adducts with excellent diastereoselectivity. Theoretical calculations explain the observed reactivity and outstanding stereocontrol, with the resulting compounds easily converted into ligands for asymmetric and catalytic transformations.
Article
Chemistry, Multidisciplinary
Nobuya Tsuji, Pavel Sidorov, Chendan Zhu, Yuuya Nagata, Timur Gimadiev, Alexandre Varnek, Benjamin List
Summary: Catalyst optimization processes often rely on qualitative assumptions of chemists based on screening data, while machine learning models using molecular properties or calculated 3D structures are time-consuming and costly. This study proposes a machine learning model based on fragment descriptors, which are fine-tuned for asymmetric catalysis and result in robust and efficient virtual screening. Through theoretical design and experimental validation, new catalysts with higher selectivities in a challenging synthesis were developed using only moderately selective training data.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
