Review
Chemistry, Multidisciplinary
Diksha Gambhir, Sanjay Singh, Ravi P. Singh
Summary: The rational combination of two catalysts has been widely used in the synthesis of biologically and pharmacologically relevant chiral compounds. This review article focuses on the achievements in asymmetric catalysis and synthesis using enamine and iminium-based dual organocatalytic systems. The combination of enamine/iminium catalysis with other organocatalytic systems has paved the way for the construction of complex chiral compounds.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Lakshmi Revati Magham, Satish B. Thopate, Abdus Samad, Rambabu Chegondi
Summary: This paper reports a method for the asymmetric desymmetrization of prochiral enal-tethered cyclohexadienones via C3-selective Friedel-Crafts alkylation, leading to the construction of complex molecules with multiple stereocentres. The reaction is triggered by the LUMO-lowering iminium activation and HOMO-raising enamine activation. The resulting bicyclic enones can undergo acid-mediated intramolecular annulation from the C2-position, yielding highly strained cyclohepta[b]indoles with excellent enantioselectivity and diastereoselectivity.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Tino P. Golub, Taichi Kano, Keiji Maruoka, Christian Merten
Summary: We present a VCD spectroscopic characterization of a chiral catalyst and show that the VCD spectra of in situ generated enamine and ex situ prepared iminium ion are different. This study highlights the potential of VCD spectroscopy in distinguishing stable intermediates and determining the dominant conformers in solution.
CHEMICAL COMMUNICATIONS
(2022)
Review
Chemistry, Multidisciplinary
Guangcai Xu, Gerrit J. Poelarends
Summary: The application of biocatalysis in challenging synthesis has greatly benefited from the development of new enzymes. By incorporating catalysis modes from synthetic chemistry, novel biocatalysts have been created, and the design of iminium catalysis plays a fundamental role in this process. It has been shown that repurposing existing enzymes or constructing artificial enzymes can promote valuable abiological transformations, demonstrating the power of combining chemomimetic biocatalyst design and directed evolution in generating new-to-nature enzymes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Shilpa Barik, Sayan Shee, Rajesh G. Gonnade, Akkattu T. Biju
Summary: The NHC-organocatalyzed [3 + 3] annulation of 2-bromoenals with fi-oxodithioesters, resulting in the enantioselective synthesis of dihydrothiopyranones, is described. The chiral a,fi-unsaturated acylazoliums generated from 2-bromoenals and carbenes react smoothly with sulfur nucleophiles to afford the sulfur heterocycles with satisfactory yields/selectivity. The regioselective formation of dihydrothiopyranones over dihydropyranones is notable.
Article
Chemistry, Organic
Chengming Wang, Lixia Liu
Summary: This transition-metal and aldehyde free, NHC-catalyzed, redox-neutral oxindole synthesis method has a broad substrate scope and good functional group tolerance, and can be easily scaled up. The reaction possibly involves NHC-facilitated single electron transfer induced intramolecular radical cyclization, and the oxindole products can be easily converted into various useful compounds.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Applied
Jasper S. Moehler, Lena K. Beiersdoerfer, Brenno Masina, Philipp Wechsler, Helma Wennemers
Summary: N-heterocyclic moieties are commonly found in pharmaceuticals and agrochemicals, but pose a challenge for metalorganic and organocatalytic transformations. This study presents tripeptide catalysts for stereoselective conjugate addition reactions between N-heterocyclic substituted aldehydes and electrophiles, achieving high yields and selectivities.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Gargi Kundu, V. S. Ajithkumar, K. Vipin Raj, Kumar Vanka, Srinu Tothadi, Sakya S. Sen
Summary: In this study, we synthesized a 6-membered saturated NHC borane adduct and investigated its reactivity. The results showed that the adduct could undergo electrophilic halogenation to form NHC boryl iodides, which further reacted with various nucleophiles to yield novel boranes with different functional groups. Additionally, the adduct reacted with Br-2/H2O to produce a dihydroxyborenium cation.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Christian B. J. Breuers, Constantin G. Daniliuc, Armido Studer
Summary: The stereoselective intramolecular dearomatizing spirocyclization of indoles via oxidative N-heterocyclic carbene (NHC) catalysis to afford indolenines bearing an all-carbon quaternary center at the 3-position is described. The reaction proceeds through the intramolecular nucleophilic addition of the indole to an in situ generated α,β-unsaturated acyl azolium.
Article
Chemistry, Inorganic & Nuclear
Jan-Erik Siewert, Andre Schumann, Tim Wellnitz, Fabian Dankert, Christian Hering-Junghans
Summary: This contribution describes the use of aryl-substituted triphosphiranes as phosphinidene transfer reagents towards N-heterocyclic carbenes, resulting in a library of N-heterocyclic carbene phosphinidene adducts. The study also introduces a new class of chelating bis(NHCP)s and investigates their coordination chemistry.
DALTON TRANSACTIONS
(2023)
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, Physical
Yuanyuan Sun, Ying Li, Xiaoyan Li, Yanli Zeng
Summary: In this study, the catalytic mechanism of mono/bis(iodoimidazolium) halogen bond donor catalysts in the Michael addition reaction was investigated. It was found that bis(iodoimidazolium) halogen bond donor catalysts showed good catalytic performance and could accelerate the reaction. The catalyzed reaction involves two steps, with two possible pathways for proton transfer, where the indirect pathway is more likely to occur.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Organic
Anna M. Costa, Alejandro Castro-Alvarez, Daniel Fillot, Jaume Vilarrasa
Summary: The energies of the CH2=CH-CH=N+R2 + HNR*(2) + CH2=CH-CH=N+R*(2) + HNR2 reactions and similar equilibria with cinnamaldehyde have been calculated and compared. The predicted order of stability of the iminium ions in very polar solvents differed from that in the gas phase. These findings can help predict the dominant iminium salts formed when conjugated carbonyl compounds are reacted with secondary amines and appropriate acids.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Yan Li, Zhilin Li, Zhiqiang Zhang
Summary: The mechanism and stereoselectivity of the NHC-catalyzed [3+4] annulation reaction were investigated using DFT calculations. The results showed that the C-C bond formation step is decisive for stereoselectivity, with the RS-configurational isomer being the main product. Non-covalent interactions play a crucial role in determining the stereochemistry of the reaction.
NEW JOURNAL OF CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Yeow-Chuan Teo, Dexter Loh, Bi-Xiang Leong, Zheng-Feng Zhang, Ming-Der Su, Cheuk-Wai So
Summary: The silicon-catalyzed hydroboration of isocyanates with pinacolborane using a specific catalyst is discussed. The activation of isocyanates by the catalyst leads to the formation of N-boryl formamides, which further react to form N-boryl methylamines and (pinB)(2)O.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Manfred Hartnagel, Armin R. Ofial, Herbert Mayr
SYNTHESIS-STUTTGART
(2023)
Article
Multidisciplinary Sciences
Timothee Constantin, Bartosz Gorski, Michael J. Tilby, Saloua Chelli, Fabio Julia, Josep Llaveria, Kevin J. Gillen, Hendrik Zipse, Sami Lakhdar, Daniele Leonori
Summary: This work presents a distinct reactivity mode enabled by quantum mechanical tunneling using a cyclohexadiene derivative as the abstractor under mild photochemical conditions. Experimental and computational studies reveal a noncanonical pathway for activation of various organic compounds.
Article
Chemistry, Multidisciplinary
Satyadeep Waiba, Kakoli Maji, Mamata Maiti, Biplab Maji
Summary: In this study, we present a simple synthesis method for valuable alpha-hydroxycarboxylic acid molecules through an acceptorless dehydrogenative coupling of ethylene glycol and primary alcohols. A stable manganese complex catalyst facilitated the reaction, which showed scalability and high yields with excellent selectivities under mild conditions. The protocol is environmentally friendly, generating only water and hydrogen gas as byproducts. Furthermore, it was successfully applied to synthesize various drugs and bioactive molecules, demonstrating its broad applicability and potential in organic synthesis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Akash Jana, Sayandip Chakraborty, Koushik Sarkar, Biplab Maji
Summary: In this study, we report the ruthenium-catalyzed synthesis of fi-alkylated secondary alcohols through the regioselective ring opening of epoxides with primary alcohols. The reaction employs alcohol as the carbon source and terminal reductant, and operates through tandem Markovnikov selective transfer hydrogenation of terminal epoxides and hydrogen transfer-mediated cross-coupling of the resulting alcohol with primary alcohol substrates. A broad scope of substrates, including drug and natural product derivatives, is demonstrated with excellent regioselectivity.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Sovan Dey, Arindam Das, Ram Naresh Yadav, Palash Jyoti Boruah, Prerana Bakli, Tania Baishya, Koushik Sarkar, Anup Barman, Ranabir Sahu, Biplab Maji, Amit Kumar Paul, Md. Firoj Hossain
Summary: A mild and eco-friendly visible-light-induced synthesis of 2-(2-hydrazinyl) thiazole from readily accessible starting materials is reported. The reaction proceeds without the need for a metal catalyst or extrinsic photosensitizer, and only requires visible light and a green solvent. The synthesized compounds showed significant antioxidant and antidiabetic properties in vitro.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Valentin Magne, Corentin Bellanger, Aqeel A. A. Hussein, Nathalie Saffon-Merceron, Sami Lakhdar
Summary: This article presents a metal-free synthesis method for aryltriphenylgermanes, which involves the reaction of triphenylgermane with fluoro(hetero)arenes under blue light irradiation in the presence of a base. The reaction proceeds under mild conditions and exhibits tolerance towards a few functionalities. The scope and limitations of this novel approach are analyzed based on preliminary mechanistic studies.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Organic
Pradip Ramdas Thorve, Kakoli Maji, Biplab Maji
Summary: In this study, a practical and regioselective synthesis of 1,2,4-triazoles utilizing amine oxidase-inspired catalysis was reported. The method is atom-economical and environmentally benign, resulting in molecules with varying structural diversity.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Multidisciplinary
Valentin Quint, Thi Hong Van Nguyen, Gary Mathieu, Saloua Chelli, Martin Breugst, Jean-Francois Lohier, Annie-Claude Gaumont, Sami Lakhdar
Summary: Regioselective phosphonation of pyridines can be achieved through activation of the pyridine ring with a Lewis acid to enable nucleophilic addition of a phosphine oxide anion, followed by oxidation with an organic oxidant. This method provides access to various 4-phosphonated pyridines with good to excellent yields. In addition, C2-phosphonated pyridines can be synthesized using strong Lewis basic phosphorus nucleophiles or strong Lewis acidic pyridines in certain cases. The mechanistic investigations help understand the factors controlling the reactivity and selectivity of this reaction.
ACS ORGANIC & INORGANIC AU
(2023)
Article
Chemistry, Organic
Hend Besrour, Matthieu Hedouin, Lina Truong, Sami Lakhdar, Hassan Oulyadi
Summary: In this study, the interaction between a diphenyliodonium salt and trivalent phosphorus compounds was investigated using {H-1, F-19, P-31} NMR and DFT calculations. The importance of blue light in the reaction was highlighted, and the formation of a phosphonium intermediate was identified. The formation of an EDA complex was characterized, and the significance of acetonitrile for the formation of this complex was demonstrated. The study was further extended to other phosphonium salt formation reactions, and the stability and photoreactivity of the complexes were investigated using DFT calculations.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Organic
Akash Jana, Sayandip Chakraborty, Koushik Sarkar, Biplab Maji
Summary: Here, we demonstrate a ruthenium-catalyzed method for synthesizing fi-alkylated secondary alcohols through the selective ring opening of epoxides with primary alcohols. The reaction uses alcohol as both the carbon source and the terminal reductant. Kinetic and labeling experiments reveal that the reaction proceeds through tandem Markovnikov selective transfer hydrogenation of terminal epoxides and hydrogen transfer-mediated cross-coupling of the resulting alcohol with primary alcohol substrates. The reaction shows a broad scope, including 40 examples of drugs/natural product derivatives, and exhibits excellent regioselectivity for various substrates.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Pramod Rai, Kakoli Maji, Sayan K. Jana, Biplab Maji
Summary: The article describes a visible-light energy-transfer catalysis method for the intermolecular dearomative [4 + 2] cycloaddition reaction of naphthalene molecules with vinyl benzenes. The method has good functional group tolerance and high yields, and can be used for late-stage modification of pharmaceutical derivatives. The effectiveness of the method is further demonstrated through post-synthetic diversification.
Article
Chemistry, Multidisciplinary
Saif Eddine Cherif, Avisek Ghosh, Saloua Chelli, Isabelle M. Dixon, Jamil Kraiem, Sami Lakhdar
Summary: This work demonstrates a novel approach to obtain the thermodynamically unfavorable Z-isomer in olefin cross-metathesis reactions by combining a classical E-selective catalyst with a readily available photocatalyst. The scope and limitations of this approach are discussed based on computational and experimental mechanistic data.
Article
Chemistry, Multidisciplinary
Kakoli Maji, Pradip Ramdas Thorve, Pramod Rai, Biplab Maji
Summary: An enantioselective ortho-C(sp(2))-H functionalization of ketones with 1,6-enynes is demonstrated using photoredox/cobalt dual catalysis. This method shows high yields, tolerance towards functional groups, and selectivity. Mechanistic studies reveal that the key steps involve visible-light mediated generation of low-valent cobalt complex, intramolecular cyclization, ortho-C-H bond insertion, and reductive elimination.
CHEMICAL COMMUNICATIONS
(2022)
Review
Chemistry, Multidisciplinary
Kuhali Das, Satyadeep Waiba, Akash Jana, Biplab Maji
Summary: The emerging field of organometallic catalysis has shifted towards research on Earth-abundant transition metals. Manganese has emerged as one of the leading competitors, playing an important role in hydrogenation, dehydrogenation, and hydroelementation reactions. Catalyst design is based on metal-ligand bifunctionality, ligand hemilability, and redox activity, resulting in different turnover numbers for product molecules.
CHEMICAL SOCIETY REVIEWS
(2022)
Review
Chemistry, Multidisciplinary
Purusattam Dey, Pramod Rai, Biplab Maji
Summary: Asymmetric catalysis utilizing chiral-at-metal complexes has emerged as an attractive strategy in recent developments, where the catalysts coordinatively activate a substrate while providing the chirality. These configurationally stable complexes have been applied in asymmetric transformations ranging from Lewis acid catalysis to photoredox and electrocatalysis. This comprehensive review focuses on the advancements in asymmetric catalysis using iridium and rhodium-based chiral-at-metal complexes as catalysts, which involve LUMO and HOMO activation, visible-light-induced asymmetric catalysis, and electricity-driven asymmetric transformations.
ACS ORGANIC & INORGANIC AU
(2022)