Article
Chemistry, Multidisciplinary
Martin Linden, Silja Hofmann, Antonia Herman, Nicole Ehler, Robin M. M. Baer, Siegfried R. R. Waldvogel
Summary: This study presents the first electrochemical approach for the direct synthesis of pyrazolines and pyrazoles from easily accessible hydrazones and dipolarophiles. The method allows for large-scale production and even conversion of highly sensitive alkenes. The use of a biphasic system with sodium iodide as a supporting electrolyte and mediator is cost-effective. Mechanistic insight is provided by the isolation of key intermediates, and the synthesis of a commercial herbicide safener further highlights the significance of this reaction.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Kou Onodera, Ryo Takashima, Yumiko Suzuki
Summary: This study utilized acylals as building blocks for selective cross-benzoin synthesis via N-heterocyclic carbene-catalyzed reactions, successfully synthesizing O-acyl cross-benzoins. The combination of ortho-substituted phenyl acylals and aromatic/aliphatic aldehydes as coupling substrates using bicyclic triazolium salts as precatalysts and potassium carbonate as a base in THF at reflux temperature selectively yielded the desired products.
Article
Chemistry, Multidisciplinary
Shi-Jun Li, Wei Fang, Jeremy O. Richardson, De-Cai Fang
Summary: Studies show that the low spin state of FeCl3/TEMPO is more favorable for hydrogen abstraction, with the N atom being the preferred hydrogen acceptor. It is discovered that dispersion interactions and nuclear tunneling can accelerate the reaction process.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Ricardo Labes, Julio C. Pastre, Richard J. Ingham, Claudio Battilocchio, Henrique M. Marcon, Mariana C. F. C. B. Damiao, Duc N. Tran, Steven V. Ley
Summary: This study reports the rapid synthesis of 2-pyrazolines from aldehydes via [3 + 2] cycloaddition of unstabilised diazo species and mono and di-substituted alkenes. The development includes semi-continuous and fully continuous methods, with a fully automated compound library generation and a graphical interface for automation control.
REACTION CHEMISTRY & ENGINEERING
(2023)
Review
Chemistry, Multidisciplinary
Purushothaman Rajeshwaran, Jonathan Trouve, Khalil Youssef, Rafael Gramage-Doria
Summary: The Wacker reaction is a significant industrial transformation that oxidizes olefins to ketones. However, it typically requires expensive palladium catalysts, which has led to the development of Wacker-type processes that avoid their use, allowing for more sustainable procedures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Md Shafaat Al Mehedi, Dare E. George, Jetze J. Tepe
Summary: This article reports the synthesis of 3,4-disubstituted 1H-pyrazoles and 3,5-disubstituted pyridines by reacting epoxides with hydrazine and ammonia, respectively. Both reactions employ Sc(OTf)3 as a Lewis acid and utilize different reaction conditions for subsequent transformations.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Lixia Yuan, Liudmila Kachalova, Muhammad E. I. Khan, Roberto Ballini, Marino Petrini, Alessandro Palmieri
Summary: In this study, fi-nitroenones were found to be effective building blocks for the synthesis of polyfunctionalized homoallylic alcohols and conjugated nitrotriene systems. The chemoselective addition of metal allylating agents to the ketone group and subsequent conversion into nitrotrienes were successfully achieved.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Han Yu, Jingjing Ren, Ya Xie, Xiaofang Su, Aiping Wang, Likai Yan, Feng Jiang, Yongge Wei
Summary: A new catalytic system using an iron compound as a molecular catalyst in water, with oxygen as the oxidant and KCl as the additive, allows for the high-yield oxidation of various alcohols to carboxylic acids under mild conditions, including active molecules and natural compounds.
Article
Chemistry, Physical
Andrew G. Breuhaus-Alvarez, Siqi Li, Nathaniel Z. Hardin, Bart M. Bartlett
Summary: Photoelectrochemical oxidation of aqueous chloride electrolytes (1 M NaCl, pH 3) to hypochlorous acid is achieved on HxWO3 semiconducting photoelectrodes under 405 nm illumination at 100 mW/cm^2 with a constant potential chronoamperometry at 1.0 V versus Ag/AgCl. The hypochlorous acid acts as an oxidation agent, leading to oxidized products (acetaldehyde, acetic acid, or acetone) when 100 mM ethanol or 2-propanol is added into the solution. Chemical oxidation of ethanol by calcium hypochlorite demonstrates that both light and the HxWO3 surface enhance the reaction rate.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Organic
Takahiro Soeta, Kota Kaneta, Yuichi Hatanaka, Tomonori Ida, Yutaka Ukaji
Summary: This paper discusses the N-heterocyclic carbene (NHC)-catalyzed redox monoacylation of 1,n-linear diols using alpha-benzoyloxyaldehydes, which resulted in moderate to good selectivities and chemical yields. The original NHC with a pyridine moiety played a crucial role in achieving good chemoselectivities, and a wide range of 1,n-linear diols were successfully applied in this reaction.
Article
Chemistry, Organic
Yaseen Hussain, Deepak Sharma, Pankaj Chauhan
Summary: An unprecedented highly stereoselective synthesis of pyrrolo[1,2-d][1,4]oxazepin-3(2H)-ones has been achieved through photoredox/N-heterocyclic carbene (NHC) relay catalysis. Substituted dibenzoxazepines and aryl/heteroaryl enals were successfully converted to dibenzoxazepine-fused pyrrolidinones with excellent diastereo- and enantioselectivities via amine oxidation and [3 + 2] annulation reactions catalyzed by organic photoredox catalysis and NHC, respectively.
Article
Chemistry, Organic
Yaseen Hussain, Deepak Sharma, Tamanna, Pankaj Chauhan
Summary: A novel and highly selective synthesis of pyrrolo[1,2-d][1,4]oxazepin-3(2H)-ones has been achieved using photoredox/N-heterocyclic carbene (NHC) relay catalysis. Various substituted dibenzoxazepines and aryl/hetereoaryl enals were efficiently converted to imines through the organic photoredox catalysis-promoted amine oxidation, followed by a NHC-catalyzed [3 + 2] annulation reaction to afford dibenzoxazepine-fused pyrrolidinones with excellent diastereo- and enantioselectivities.
Article
Chemistry, Organic
Vasiliy M. Muzalevskiy, Zoia A. Sizova, Vasiliy V. Panyushkin, Vyacheslav A. Chertkov, Victor N. Khrustalev, Valentine G. Nenajdenko
Summary: A novel class of trifluoromethyl building blocks was efficiently synthesized and a possible reaction mechanism was proposed. This strategy allows for the synthesis of trifluoromethylated pyrazolines and pyrazoles, enabling the synthesis of derivatives of known drugs.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Giacomo Rigoni, Pamela V. S. Nylund, Martin Albrecht
Summary: The chemistry of N-heterocyclic carbenes with Earth-abundant manganese has been studied, focusing on low-valent systems for reductive catalysis. In this study, imidazole- and triazole-derived carbenes were modified with phenol substituents to access higher-valent Mn(iii) complexes. These complexes showed catalytic activity for alcohol oxidation using tBuOOH as the oxidant, with complex 2 being slightly more active and more robust towards deactivation compared to complex 1. Mechanistic investigations supported the formation of a manganese(v) oxo system as the active species and turnover-limiting hydrogen atom abstraction.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Organic
Bo Han, Hongmei Jiao, Rong Chen, Yuqi Zhang, Jijiang Wang
Summary: The first example of NHC (N-heterocyclic carbene) ligand-promoted reduction of imines and azobenzenes with a homogeneous silver catalyst is reported. The use of PhSiH3 induces hydrogenation of imines and azobenzenes, and the 1 mol% NHC-Ag precatalyst enables the retention of reducible functionalities and compatibility of sensitive groups, offering a mild and practical method for amine preparation with high turnover numbers (up to 9500). It has also been shown that the IPrAgCl/PhSiH3 combination is responsible for the selective C=O reduction of aldehyde and ketone analogues.
ORGANIC CHEMISTRY FRONTIERS
(2023)