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
Biochemistry & Molecular Biology
Martyna Malinowska, Anna Zawisza
Summary: Bifunctional thioureas and bifunctional thiosquaramides were used as organocatalysts for the first time in the asymmetric Betti reaction, resulting in high yields and enantioselectivity for the synthesis of chiral aminoarylnaphthols and enantioenriched 3-amino-2-oxindoles.
Article
Chemistry, Organic
Viera Polackova, Dominika Kristofikova, Boglarka Nemethova, Renata Gorova, Maria Meciarova, Radovan Sebesta
Summary: Bifunctional N-sulfinylureas and thioureas with an appended pyrrolidine unit were synthesized and evaluated as organocatalysts in Michael additions. The N-sulfinyl-urea catalyst was more efficient than the corresponding thiourea, achieving up to 98% ee enantioselectivities for some substrates. The mode of action was elucidated through DFT calculations, confirming a dual activation mode involving enamine activation of aldehydes and hydrogen-bond activation of nitroalkenes.
BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Hyo-Jun Lee, Keiji Maruoka
Summary: This article provides detailed insights into the applications of four types of amino Tf-amide catalysts in asymmetric transformations, including stereoselective reactions catalyzed by enamine intermediates, asymmetric direct Mannich reactions catalyzed by aliphatic Tf-amides, asymmetric direct aldol reactions and conjugate additions catalyzed by primary-amino aliphatic Tf-amides, and asymmetric transformations catalyzed by modified amino aromatic Tf-amides.
Article
Chemistry, Applied
Andreas Eitzinger, Jan Otevrel, Victoria Haider, Antonio Macchia, Antonio Massa, Kirill Faust, Bernhard Spingler, Albrecht Berkessel, Mario Waser
Summary: In this study, chiral 3,3-disubstituted isoindolinones were synthesized using ammonium salt catalysis, yielding a variety of differently substituted CF3S- and RS-derivatives with high enantioselectivities. Additionally, a racemic synthesis of F-containing products was achieved for the first time, producing a stable alpha-F-alpha-amino acid derivative.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Organic
Ryuichi Nishiyori, Megumi Okada, John R. J. Maynard, Seiji Shirakawa
Summary: This study demonstrated the successful development of highly enantioselective bromolactonizations of 4-aryl-4-pentenoic acids using BINOL-derived chiral bifunctional sulfide catalysts, highlighting the importance of the bifunctional design in chiral sulfide catalysts. The catalytic asymmetric reaction system could also be applied to highly stereoselective desymmetrizing bromolactonizations, showing promising potential for further applications in asymmetric synthesis.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
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
Daniel Rozsar, Alistair J. M. Farley, Iain McLauchlan, Benjamin D. A. Shennan, Ken Yamazaki, Darren J. Dixon
Summary: This article describes the enantioselective intermolecular conjugate addition of nitroalkanes to unactivated alpha,beta-unsaturated esters catalyzed by a bifunctional iminophosphorane (BIMP) superbase. It provides a straightforward approach to the synthesis of pharmaceutically relevant enantioenriched gamma-nitroesters with unprecedented selectivity. The methodology demonstrates broad substrate scope and has been successfully applied on a gram scale with reduced catalyst loading, allowing for catalyst recovery.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Ken Okuno, Takumi Nakamura, Seiji Shirakawa
Summary: This study reports the synthesis and asymmetric catalysis of chiral bifunctional selenides and selenonium salts, which promote asymmetric halocyclizations and phase-transfer conjugate additions.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Physical
Zhiwei Jiang, Martial Toffano, Giang Vo-Thanh, Chloee Bournaud
Summary: An efficient and flexible synthesis of a new class of chiral bifunctional NHC catalyst has been reported, which promotes highly diastereoselective trans-cyclopentannulation of enals and enones with good yields and excellent enantioselectivity. This methodology could be applied to a large variety of substrates.
Article
Chemistry, Medicinal
Ryuichi Nishiyori, Ken Okuno, Bun Chan, Seiji Shirakawa
Summary: BINOL-derived chiral bifunctional sulfide and selenide catalysts have been found to be effective in enantioselective bromolactonization reactions. However, in enantioselective iodolactonization reactions, the products obtained with chiral sulfide catalysts were unexpectedly racemic. Further investigation revealed the importance of both a selenide moiety and a hydroxy group in chiral bifunctional selenide catalysts for achieving enantioselective iodolactonizations.
CHEMICAL & PHARMACEUTICAL BULLETIN
(2022)
Article
Chemistry, Organic
Eddy Jimenez, Margarita Cantu-Reyes, Miguel Flores-Ramos, Carlos A. Roman-Chavarria, Howard Diaz-Salazar, Marcos Hernandez-Rodriguez
Summary: The asymmetric ring opening of azlactones via dynamic kinetic resolution (DKR) was studied by comparing different thioureas. The catalysts with additional chiral centers outperformed Takemoto's thiourea. The difference in yield and selectivity between the fluorinated and non-fluorinated catalysts was minimal. The analysis of calculated transition states showed that the hydrogen bond (HB) between the NH linked to the 1-arylethyl and the negatively charged oxygen in the benzyloxy ion was the longest in the HB network, indicating that the substituents and the HB donor ability of the chiral fragment attached to the thiourea were not important in the reaction.
Article
Biochemistry & Molecular Biology
Xiao-Yan Dong, Da-Ming Du
Summary: This paper investigated the organocatalytic asymmetric 1,4-Michael addition reaction of azadienes and alpha-thiocyanoindanones, successfully synthesizing a series of chiral thiocyano compounds. By describing a possible reaction mechanism, it broadens the scope of application of azadiene substrates.
Review
Chemistry, Physical
Nilanjana Majumdar
Summary: Catalytic asymmetric transformation is a powerful strategy for synthesizing diverse nonracemic molecular entities. Carboxylic acids have been explored as building blocks in this area, and significant advancements have been made in the last three decades. They can act as both C- and O-nucleophiles, as well as electrophiles, in asymmetric reactions under catalytic conditions.
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)
Article
Chemistry, Organic
Chandra Bhushan Tripathi, Santanu Mukherjee
Article
Chemistry, Multidisciplinary
Chandra Bhushan Tripathi, Tsuyoshi Ohtani, Michael T. Corbett, Takashi Ooi
Article
Chemistry, Organic
Chandra Bhushan Tripathi, Santanu Mukherjee
JOURNAL OF ORGANIC CHEMISTRY
(2012)
Article
Chemistry, Organic
Chandra Bhushan Tripathi, Satavisha Kayal, Santanu Mukherjee
Article
Chemistry, Organic
Chandra Bhushan Tripathi, Santanu Mukherjee
Article
Chemistry, Organic
Chandra Bhushan Tripathi, Santanu Mukherjee
Article
Chemistry, Organic
Qumruddeen, Arun Yadav, Ruchir Kant, Chandra Bhushan Tripathi
JOURNAL OF ORGANIC CHEMISTRY
(2020)
Article
Chemistry, Multidisciplinary
Arun Yadav, Sabhya Sandha, Chandra Bhushan Tripathi
Summary: An organocatalytic photoinduced 1,2-carbofunctionalization strategy has been developed that enables regioselective and efficient 1,2-carboisothiocyanation of conjugated dienes without the need for exogenous photocatalysts or additives. The reaction is proposed to proceed through EDA complexation between the diene and TMSNCS.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Shiv Shankar Patel, Dileep Kumar, Chandra Bhushan Tripathi
Summary: This research addresses the generation of alkyl radicals under mild conditions through photoinduced Brönsted acid catalysis. The optimized protocol does not require organic dyes or transition metal photocatalysts. Functionalized arylmethane derivatives are obtained in high yield under blue light irradiation with diphenyl phosphate as a catalyst and dihydropyridine derivatives as a radical source.
CHEMICAL COMMUNICATIONS
(2021)
