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Magnus Rueping – 1st expert on this subject based on the ideXlab platform
enantio and diastereoselective access to distant stereocenters embedded within tetrahydroxanthenes utilizing ortho quinone methides as reactive intermediates in asymmetric Bronsted Acid catalysisAngewandte Chemie, 2014Co-Authors: Chienchi Hsiao, Hsuanhung Liao, Magnus RuepingAbstract:
A protocol for the highly enantioselective synthesis of 9-substituted tetrahydroxanthenones by means of asymmet- ric Bronsted Acid catalysis has been developed. A chiral binol- based N-triflyphosphoramide was found to promote the in situ generation of ortho-quinone methides and their subsequent reaction with 1,3-cyclohexanedione to provide the desired products with excellent enantioselectivities. In addition, a highly enantio- and diastereoselective Bronsted Acid cata- lyzed desymmetrization of 5-monosubstituted 1,3-dicarbonyl substrates with ortho-quinone methides gives rise to valuable tetrahydroxanthenes containing two distant stereocenters.
asymmetric Bronsted Acid catalysis in aqueous solutionChemical Science, 2010Co-Authors: Magnus Rueping, Thomas TheissmannAbstract:
A biologically inspired reaction design leads to the development of the first highly enantioselective Bronsted Acid catalysed reaction in aqueous solution.
unifying metal and Bronsted Acid catalysis concepts mechanisms and classificationsChemistry: A European Journal, 2010Co-Authors: Magnus Rueping, Rene M Koenigs, Iuliana AtodireseiAbstract:
Asymmetric catalysis is a key feature of modern synthetic organic chemistry. Traditionally, different combinations of ligands and metals are used to perform highly enantioselective reactions. Since the renaissance of organocatalysis in the early 2000s, tremendous improvement in the field of metal-free catalysis has been achieved. Recently, the combination of transition metals and organocatalysts has allowed the development of new protocols enabling transformations that could not previously be realized. This article aims to present the latest contributions in the field of combined chiral Bronsted Acid and metal catalyzed reactions, highlighting the advantages of these catalytic systems as well as describing the uncertainties regarding the molecular structure of the catalytically active species and the reaction mechanisms.
Liu-zhu Gong – 2nd expert on this subject based on the ideXlab platform
Isothiourea and Bronsted Acid Cooperative Catalysis: Enantioselective Construction of Dihydropyridinones.Organic Letters, 2020Co-Authors: Yu-chen Zhang, Rui-long Geng, Jin Song, Liu-zhu GongAbstract:
Asymmetric annulation of bench-stable α,β-unsaturated aryl esters with enamines was realized via cooperative catalysis of chiral isothiourea and Bronsted Acid. This reaction proceeds via a chiral α…
cascade hydroamination redox reaction for the synthesis of cyclic aminals catalyzed by a combined gold complex and Bronsted AcidChemistry: A European Journal, 2013Co-Authors: Yuping He, Dian-feng Chen, Hua Wu, Jie Yu, Liu-zhu GongAbstract:
Relay catalysis: An unprecedented protocol for the synthesis of cyclic aminals has been realized under the relay catalysis of a gold(I)/Bronsted Acid binary system to generate cyclic aminals in excellent yields of up to 99 % with moderate to high diastereoselectivity (see scheme; up to 95:5 d.r.).
Bronsted Acid rhodium ii cooperative catalytic asymmetric three component aldol type reaction for the synthesis of 3 amino oxindolesChemistry: A European Journal, 2013Co-Authors: Xiaolei Lian, Liu-zhu GongAbstract:
Cooperation is key! Chiral Bronsted Acid/rhodium(II) cooperative catalysis enabled an enantioselective three-component aldol-type reaction of 3-diazo oxindoles and anilines with glyoxylates to give highly functionalized and structurally diverse 3-amino oxindoles in high stereoselectivity (>20:1 d.r., 99 % ee; see scheme).
Hisashi Yamamoto – 3rd expert on this subject based on the ideXlab platform
chiral Bronsted Acid as a true catalyst asymmetric mukaiyama aldol and hosomi sakurai allylation reactionsJournal of the American Chemical Society, 2015Co-Authors: Hisashi YamamotoAbstract:
Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Bronsted Acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi–Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. 29Si and 31P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Bronsted Acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric Acid analogues.
super Bronsted Acid catalysisChemical Communications, 2011Co-Authors: Cheolhong Cheon, Hisashi YamamotoAbstract:
Bronsted Acid catalysis has emerged as a new class of catalysis in modern organic synthesis. However, in order to make the utility of the Bronsted Acid catalysis as broad as the well-developed Lewis Acid catalysis, it is desirable to develop Bronsted Acids demonstrating both high reactivities and selectivities. In this feature article, we will present our achievement in the design and development of strong Bronsted Acids and their application to organic reactions. Furthermore, we will describe the Tf2NH-catalyzed Mukaiyama aldol reaction of super silyl enol ethers. We also will highlight the differences in reactivity and chemo- and stereo-selectivity between Bronsted and Lewis Acid catalysis.
a Bronsted Acid catalyst for the enantioselective protonation reactionJournal of the American Chemical Society, 2008Co-Authors: Cheolhong Cheon, Hisashi YamamotoAbstract:
A highly reactive and robust chiral Bronsted Acid catalyst, chiral N-triflyl thiophosphoramide, was developed. The first metal-free Bronsted Acid catalyzed enantioselective protonation reaction of silyl enol ethers was demonstrated using this chiral Bronsted Acid catalyst. The catalyst loading could be reduced to 0.05 mol % without any deleterious effect on the enantioselectivity.