Review
Chemistry, Multidisciplinary
Achille Antenucci, Stefano Dughera, Polyssena Renzi
Summary: This review discusses the synthesis of organic chiral catalysts, presents a classification of catalyst scaffolds based on their E factor, and proposes the global E factor (E-G factor) as a new green chemistry metric.
Article
Polymer Science
Tianfo Guo, Haoying Tong, Zhenjiang Li, Jie Sun, Yongqiang Li, Rui Yan, Bo Liu, Zhihao Zhang, Yuejia Zhu, Kai Guo
Summary: A polybenzoxazine (PBz) anchored with an N-4'-pyridyl group on the backbone was prepared and characterized, showing efficient catalytic activity in acylation, silylation, and tritylation reactions at room temperature. The catalyst exhibited high catalytic activity, good yields, and retained 85% activity after 4 recycles, demonstrating its potential as a versatile polymeric catalyst for various reactions.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Davide Campagna, Robert Goestl
Summary: This study reports a mechanochemical protecting group for secondary amines that can be activated in polymers through force-induced reactions. The research demonstrates that this protecting group can produce free amines in polymers through bond scission, similar to its photochemical counterpart. Additionally, the protecting group is applied in a force-activated organocatalytic reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Martin Berger, Davide Carboni, Paolo Melchiorre
Summary: The study presents the first catalytic enantioselective conjugate addition of allyl groups to alpha, beta-unsaturated aldehydes, utilizing the visible-light-excitation of chiral iminium ions to activate allyl silanes toward the formation of allylic radicals. This radical mechanism overcomes issues seen in traditional conjugate allylation processes and selectively installs prenyl fragments at the beta-carbon of enals.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Titouan Desrues, Jeremy Merad, Daniela Andrei, Jean-Marc Pons, Jean-Luc Parrain, Maurice Medebielle, Adrien Quintard, Cyril Bressy
Summary: This study reported an enantioselective organocatalyzed acylation of alpha,alpha-difluorohydrins using a commercially available chiral isothiourea, greatly improving the enantioselectivity of the kinetic resolution process through electrostatic fluorine-cation interactions. The method allows for the synthesis of various fluorinated alcohols with exquisite enantiocontrol, such as 4,4-difluoro-1,3-diols, as well as demonstrated compatibility between aromatic and fluorinated groups in providing enantioenriched adducts.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
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, Multidisciplinary
Ayako Kurose, Yuto Ishida, Goki Hirata, Takashi Nishikata
Summary: This study developed an efficient method for the tertiary alkylation of a ketone using an alpha-bromocarbonyl compound as the tertiary alkyl source in a combined Cu-organocatalyst system, allowing the addition of a tertiary alkyl radical to an enamine. Mechanistic studies indicated that the catalytically generated enamine plays a key role in the catalytic cycle, enabling the synthesis of substituted 1,4-dicarbonyl compounds containing quaternary carbons with various alkyl chains.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Qing-Zhu Li, Rong Zeng, Peng-Shuai Xu, Xin-Hang Jin, Chuan Xie, Qi-Chun Yang, Xiang Zhang, Jun-Long Li
Summary: In this study, a cross-coupling reaction of aldehydes with unactivated alkyl halides was developed through N-heterocyclic carbene catalysis, enabling the synthesis of various ketones. This method offers the advantages of mild reaction conditions and readily available starting materials, and has been successfully applied in the functionalization of pharmaceutical derivatives.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Qing-Zhu Li, Rong Zeng, Peng-Shuai Xu, Xin-Hang Jin, Chuan Xie, Qi-Chun Yang, Xiang Zhang, Jun-Long Li
Summary: Catalytic cross-coupling reaction of aldehydes with unactivated alkyl halides was achieved via N-heterocyclic carbene catalysis. This method enables rapid synthesis of various ketones from readily available starting materials under mild conditions. The organocatalytic system was successfully applied in the late-stage functionalization of pharmaceutical derivatives. Mechanistic investigations suggest a closed-shell nucleophilic substitution mechanism for this reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Multidisciplinary Sciences
Geun Seok Lee, Beomsoon Park, Soon Hyeok Hong
Summary: In this study, an efficient method for the stereoretentive direct cross-coupling of chiral amino acid chlorides and unactivated C(sp(3))-H hydrocarbons was achieved via photoredox catalysis. The strategic generation of an N-acyllutidinium intermediate facilitated the synthesis of chiral amino ketones with retention of stereochemistry.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Applied
Claire Segovia, Jeremy Godemert, Jean-Francois Briere, Vincent Levacher, Sylvain Oudeyer
Summary: An organocatalyzed one-pot sequential deracemization of aromatic ketones with a stereogenic center at the alpha-position was achieved through an acid-base strategy, in which enantioselective protonation reaction played a key role. This protocol provides enantioenriched ketones with up to 89% ee without isolating sensitive intermediates like silyl enolates. Water was found to be crucial in this process. This one-pot sequence serves as a valuable extension to previously reported chemically driven red-ox protocols, expanding the range of molecules eligible for deracemization.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Huyan Zhou, Lu Zhang, Peng Wen, Yang Zhou, Yucheng Zhao, Qiaoqiao Zhao, Yu Gu, Ruopeng Bai, Mao Chen
Summary: In this study, photoredox-mediated reversible-deactivation radical polymerization (RDRP) was developed by activating (hetero)aryl sulfonyl chloride (ArSO2Cl) initiators with pyridines and designing a novel bis(phenothiazine)arene catalyst. The in situ formed sulfonyl pyridinium intermediates effectively promote controlled chain-growth from ArSO2Cl, enabling access to various well-defined polymers with high initiation efficiencies and controlled dispersities under mild conditions. This versatile method allows ON/OFF temporal control, chain-extension, and facile synthesis of different polymer brushes via organocatalyzed grafting reactions from linear chains. Time-resolved fluorescence decay studies and calculations support the reaction mechanism. This work provides a transition-metal-free RDRP to tailor polymers with readily available aromatic initiators, and will promote the design of polymerization leveraged from photoredox catalysis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Janik Kaufmann, Jonas Wolf, Alexander Heckel
Summary: The possibilities of dicyanocoumarin (DCCM)-modified oligonucleotides have expanded to include not only release and activation with green light (OFF?ON), but also fragmentation after exposure to green light (ON?OFF). The use of rigidified DCCM 5'-caps, such as those with ATTO 390 motif or julolidine core, has shown improved performance and compatibility with copper(I)-catalyzed alkyne-azide cycloadditions (CuAACs). These modifications allow for efficient caging through cyclization or other bioconjugation reactions, and their planarization even results in an additional red-shift, making them suitable for biological applications.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Noe Fanjul-Mosteirin, Vicente del Amo
Summary: There is a significant use of volatile organic compounds (VOCs) nowadays, which have serious disadvantages. Developing alternative reaction media to replace VOCs is crucial. Deep eutectic solvents (DESs) have garnered attention as surrogates, with this review summarizing organocatalytic transformations carried out in DESs for comparison with traditional VOC solvents.
Article
Chemistry, Multidisciplinary
Sabrina D. Pueschmann, Philipp Fruehwirt, Michael Pillinger, Andreas Knoechl, Marlene Mikusch, Judith Radebner, Ana Torvisco, Roland C. Fischer, Norbert Moszner, Georg Gescheidt, Michael Haas
Summary: The synthesis of mixed tetraacylgermanes with a nonsymmetric substitution pattern results in increased solubility and broadened absorption bands, enhancing their photoactivity. These compounds exhibit efficient photobleaching when using an LED emitting at 470 nm, making them ideal photoinitiators for various applications.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Giorgos N. Papadopoulos, Maroula G. Kokotou, Nikoleta Spiliopoulou, Nikolaos F. Nikitas, Errika Voutyritsa, Dimitrios I. Tzaras, Nikolaos Kaplaneris, Christoforos G. Kokotos
Article
Chemistry, Organic
Nikolaos F. Nikitas, Errika Voutyritsa, Petros L. Gkizis, Christoforos G. Kokotos
Summary: A simple, photochemical, and metal-free protocol for the atom transfer radical addition (ATRA) of bromotrichloromethane onto various alkenes is described, with phenylglyoxylic acid proving to be the most suitable photoinitiator. This protocol can be expanded into a wide substrate scope of aliphatic olefins with various functional groups, leading to good to excellent yields of the corresponding products.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Nikolaos F. Nikitas, Maria A. Theodoropoulou, Christoforos G. Kokotos
Summary: This study presents a new photochemical methodology for the reaction between N,N-dimethylanilines and N-substituted maleimides, using benzaldehyde as the photoinitiator. Various substituted N,N-dimethylanilines and N-substituted maleimides were successfully converted into corresponding adducts in moderate to high yields.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Elpida Skolia, Mary K. Apostolopoulou, Nikolaos F. Nikitas, Christoforos G. Kokotos
Summary: An efficient, green, and metal-free photochemical protocol for synthesizing benzimidazoles has been developed using 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator and CFL lamps as the light source. Good to high yields of the corresponding benzimidazoles were obtained, and mechanistic studies were conducted to determine the plausible reaction mechanism.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Nikolaos F. Nikitas, Mary K. Apostolopoulou, Elpida Skolia, Anna Tsoukaki, Christoforos G. Kokotos
Summary: A cost-effective and straightforward photochemical method has been developed for the activation of aromatic aldehydes, leading to the conversion into various products including a drug for depression and social anxiety. Detailed mechanistic studies have been conducted to determine a plausible mechanism for the reaction.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Medicinal
Charikleia S. Batsika, Christiana Mantzourani, Dimitrios Gkikas, Maroula G. Kokotou, Olga G. Mountanea, Christoforos G. Kokotos, Panagiotis K. Politis, George Kokotos
Summary: The discovery of saturated oxo fatty acids (SOFAs) has shown potential in inhibiting the growth of human lung carcinoma cells. Particularly, 6OSA and 7OSA exhibited the most significant inhibitory effect on cell growth, affecting crucial regulators of cell growth and proliferation.
JOURNAL OF MEDICINAL CHEMISTRY
(2021)
Article
Chemistry, Applied
Zdravko Dzambaski, Aleksandra M. Bondzic, Ierasia Triandafillidi, Christoforos G. Kokotos, Bojan P. Bondzic
Summary: Organic single-electron oxidant in the presence of diarylprolinol silylether type catalyst can transform electron-rich enamines to iminium ions, which then participate in a subsequent Michael-initiated ring-closure reaction with in situ nucleophile to yield stereodefined cyclopropanes from saturated aldehydes. This one-pot transformation exemplifies the use of saturated aldehydes in coupled processes, providing high yields and selectivities.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Multidisciplinary
Nikoleta Spiliopoulou, Petros L. Gkizis, Ierasia Triandafillidi, Nikolaos F. Nikitas, Charikleia S. Batsika, Aikaterini Bisticha, Christoforos G. Kokotos
Summary: In this paper, we restudied the mechanism of action of phenylglyoxylic acid (PhCOCOOH) in photochemical reactions and proposed a unified mechanism. Additionally, we compared its action as a photoinitiator with known and commercially available photoinitiators.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Ierasia Triandafillidi, Nikolaos F. Nikitas, Petros L. Gkizis, Nikoleta Spiliopoulou, Christoforos G. Kokotos
Summary: This paper investigates the photocatalytic reaction between alkynes and maleimides, comparing the reactivity differences between N-alkyl and N-aryl maleimides. The results show that using hexafluoroisopropanol or trifluoroacetic acid as solvents can achieve high yields in the reaction.
Article
Biochemistry & Molecular Biology
Giorgos S. Koutoulogenis, Nikoleta Spiliopoulou, Christoforos G. Kokotos
Summary: A novel, mild, metal-free procedure for the C-H acetalization of O-heterocycles via visible light activation using phenylglyoxylic acid as the photoinitiator is presented. Biomass-derived O-heterocycles such as THF can be used, and a variety of alcohols with different functionalities can be successfully employed to afford the desired acetals in high yields. Convenient acidic deprotection was also carried out.
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
(2022)
Review
Chemistry, Multidisciplinary
Elpida Skolia, Petros L. Gkizis, Chistoforos G. Kokotos
Summary: This review summarizes the photochemical protocols for the oxidation of sulfides to sulfoxides using oxygen or air as the oxidant. The review includes a historical overview, key mechanistic studies and proposed mechanisms, as well as categorizing different catalytic systems in the literature.
Article
Chemistry, Multidisciplinary
Ierasia Triandafillidi, Maroula G. Kokotou, Dominik Lotter, Christof Sparr, Christoforos G. Kokotos
Summary: The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides essential products and intermediates in a sustainable manner. A specific atropisomeric two-axis aldehyde was identified for high-yielding epoxidations of cyclic and acyclic alkenes, resulting in high catalytic efficiencies due to the proximity of the aldehyde and backbone residues. Mechanistic studies suggest a non-radical alkene oxidation by an aldehyde-derived dioxirane intermediate generated from hydrogen peroxide through the Payne and Criegee intermediates.
Review
Chemistry, Organic
Nikolaos F. Nikitas, Petros L. Gkizis, Christoforos G. Kokotos
Summary: Photoorganocatalysis is recognized as an important aspect of photochemistry and catalysis in organic chemistry, with aromatic ketones playing a significant role. Thioxanthone (TX) stands out for its unique properties in photochemistry, with high triplet energy and long triplet lifetime, making it effective in merger reactions with metal complexes. This review discusses the photophysical properties of TX and its applications in various photochemical reactions, particularly in polymerization and organic transformations.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Nikoleta Spiliopoulou, Christoforos G. Kokotos
Summary: A new photochemical approach for the synthesis of symmetrical and non-symmetrical disulfides is described, utilizing mild, inexpensive and green conditions. The method involves the use of phenylglyoxylic acid as the photoinitiator, household bulbs as the light source, and a simple inorganic salt as the additive, resulting in excellent yields of the products.
Article
Multidisciplinary Sciences
Ierasia Triandafillidi, Errika Voutyritsa, Christoforos G. Kokotos
PHYSICAL SCIENCES REVIEWS
(2020)
