Article
Chemistry, Applied
Irma Garcia-Monzon, Jorge Borges-Gonzalez, Tomas Martin
Summary: The heterogenization of homogeneous catalysts onto a solid support is a crucial step towards sustainable chemistry. In this study, we developed a series of polymer-supported tetrahydropyran-based hybrid dipeptides as active catalysts for the enantioselective Michael addition of aldehydes to beta-nitrostyrenes. The optimal anchor position and orientation between the catalyst and solid support, as well as the linker length, were carefully designed to enhance the catalytic efficiency. These supported catalysts exhibited high yields and enantiomeric excesses, and detailed deactivation studies provided important insights for prolonging their useful life.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
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.
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
Esteban Matador, Javier Iglesias-Siguenza, David Monge, Pedro Merino, Rosario Fernandez, Jose M. Lassaletta
Summary: A highly enantio- and diastereoselective thiourea-catalyzed dearomatization of isoquinolines has been developed using N-tert-butylhydrazones as key neutral reagents, leading to the formation of appealing dihydroisoquinoline derivatives with excellent stereocontrol. Experimental and computational data support the generation of highly ordered complexes that play a crucial role in the selective and high-yielding transformations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Applied
Jen-Yu Kuan, I-Ting Chen, Hsuan Lin, Jeng-Liang Han
Summary: We have developed a substrate-dependent, regio- and stereocontrolled diversity-oriented organocatalytic vinylogous Michael addition/cyclization cascade of 2-alkylidene indane-1,3-diones with enals, using secondary amines as the catalyst. This method allows for the selective synthesis of spiroindane-1,3-diones, tetrahydrofluoren-9-one derivatives, and benzofused oxabicyclo[3.3.1]nonanes. Plausible catalytic pathways have been proposed, and DFT calculations have clarified the mechanisms involved.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Applied
Zaneta A. Mala, Mikolaj J. Janicki, Robert W. Gora, Krzysztof A. Konieczny, Rafal Kowalczyk
Summary: Dithiomalonates have been shown to be active nucleophiles in stereoselective additions, with Cinchona squaramides facilitating chirality transfer and mechanochemical approach proving to be effective.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Review
Chemistry, Multidisciplinary
Corinne Coutant, Paul De Bonfils, Pierrick Nun, Vincent Coeffard
Summary: The advent of asymmetric organocatalysis has revolutionized the way chemists create or break chemical bonds, enabling new strategies for enantioselective functionalization. This success is attributed to various activation modes and the availability of numerous chiral organic catalysts. Selective functionalization of compounds with multiple activation sites, such as cyclohexanone-derived dienones, has also contributed to breakthroughs in this field. These compounds can undergo diverse transformations and offer new opportunities for natural product synthesis. This review focuses on intermolecular functionalization of (cross)-conjugated cyclohexanone-derived compounds using asymmetric organocatalysis.
Article
Chemistry, Multidisciplinary
Muhammad Sohail, Fujie Tanaka
Summary: The DYKAT reactions can transform dihydrobenzofuranone derivatives into spirooxindole derivatives with high enantioselectivities and yields, regardless of the stereochemistry of the starting materials.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Fangfang Guo, Jiean Chen, Yong Huang
Summary: Recently, chiral N-heterocyclic carbenes (NHCs) have been established as powerful catalysts for enantioselective bond-forming processes via noncovalent interactions. A bifunctional NHC with an embedded hydrogen-bonding motif has been reported in this study, showing remarkable tolerance of various Michael acceptors in an asymmetric aza-conjugate addition reaction, with catalytic efficiency far exceeding that of the benchmark tertiary amine-thiourea scaffold.
Article
Chemistry, Physical
Alexey A. Tsygankov, Denis Chusov
Summary: By using a fluoride anion source, well-known transition metal catalysts can be transformed into high-performance versions, increasing catalytic activity, particularly in reactions such as asymmetric cyanation of aldehydes, asymmetric Michael addition, and synthesis of cyclic carbonates.
Article
Chemistry, Applied
Eugenia Marques-Lopez, Isaac G. Sonsona, Miryam Garces-Marin, M. Concepcion Gimeno, Raquel P. Herrera
Summary: In this study, the potential of phosphites as nucleophiles for the asymmetric synthesis of chiral chromene derivatives was explored. By employing asymmetric organocatalyzed phospha-Michael addition, chiral chromenylphosphonates were synthesized using a bifunctional squaramide. The optimized protocol provided good reactivity with yields of up to 95% and chiral products with an enantiomeric excess of up to 98%.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Vasco Corti, Mathias Kirk Thaegersen, Valdemar Juel Enemaerke, Nomaan M. Rezayee, Casper L. Barlose, Karl Anker Jorgensen
Summary: The first atroposelective aminocatalytic methodology for the construction of C-N atropisomers is described. By directly coupling indole-2-carboxaldehydes to ortho-quinones, a new library of functionalized and enantioenriched C-N atropisomers was obtained using a designed and synthesized aminocatalyst. The synthetic utility of these atropisomers was demonstrated through various transformations.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Zhibin Guo, Daehyun Oh, Min Sagong, Jewon Yang, Geumwoo Lee, Hyeung-geun Park
Summary: An efficient method for synthesizing chiral malonates was established using enantioselective phase transfer catalysis. The a-alkylation reaction of 2,2-diphenylethyl tert-butyl a-methylmalonates with (S,S)-3,4,5-trifluorophenyl-NAS bromide as a phase-transfer catalyst successfully yielded corresponding a-methyl-a-alkylmalonates. These compounds are versatile chiral building blocks with a quaternary carbon center, obtained in high chemical yields (up to 99%) and excellent enantioselectivities (up to 98% ee). Selective hydrolysis of a,a-dialkylmalonates to the corresponding chiral malonic monoacids was achieved using basic (KOH/MeOH) and acidic conditions (TFA/CH2Cl2), demonstrating the practicality of the method.
FRONTIERS IN CHEMISTRY
(2023)
Article
Chemistry, Organic
Abhisek Midya, Laxman Devidas Khalse, Prasanta Ghorai
Summary: In this study, an amine-catalyzed reductive aldol-condensation followed by an intramolecular reductive Michael-addition cascade was demonstrated, using Hantzsch ester as a hydride source to a keto-bis-enone, leading to the synthesis of enantio- and diastereoselective benzannulated diquinanes with three consecutive stereocenters, including an all-carbon quaternary formyl stereocenter. Interestingly, changing the tether from an aliphatic to an aromatic moiety resulted in a change in reactivity, where an asymmetric aldol reaction, followed by an iminium/enamine isomerization and diastereoselective Michael addition reaction, resulted in the formation of a bis-benzannulated diquinane with vicinal congested quaternary chiral centers.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Applied
Gianluca Casotti, Vincenzo Rositano, Anna Iuliano
Summary: Stabilised arylzinc iodide prepared by direct insertion of zinc into aryl iodides, were successfully applied as nucleophiles in the Hayashi Rh-catalysed enantioselective conjugate addition to enones, with high yields and 99% ee of the addition product. The general applicability of the protocol was confirmed by using different arylzinc iodides and enones, as well as organometallic reagents with both halogen and electrophilic groups.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
