Field Of Organic Chemistry Research Articles

Cationic Ruthenium for C-H Activation Reactions

Abstract: C-C bond formation in a regiospecific and atom economic manner has been a challenge, which was tried to be resolved through directing group and organometals-based C-H activation strategy. The C-H activation and its advantages are well explored in the field of organic chemistry, with the relevant mechanistic approach of the regioselective C-H activation of the aryl group. Organometals like Ru, Pd, Pt, Ni, etc. have been best discovered for the innate C-H activation where the pre-activation of the inert C-H bond was not found necessary. In the progress of these reactions through organometals, the various forms of ruthenium have been tried with the different directing groups as well as the substrate. Here in we are focusing mainly on cationic ruthenium, and its use in the C-H activation. The cationic ruthenium shows unique characteristics like reactivity with an inert substrate, which is been highlighted here in the examples. The formation and its, mechanistic role is also exemplified with the diagrammed representation of C-H activation and its catalytic cycle. The application of the cationic ruthenium will give complete knowledge about cationic ruthenium and its application in C-H activation.

Peningkatan Kompetensi Profesional MGMP Kimia Kabupaten Pasaman Sebagai Pembina Siswa Menghadapi Olimpiade Sains Nasional (OSN)

IMPROVİNG THE PROFESSİONAL COMPETENCE OF MGMP CHEMİSTRY İN PASAMAN REGENCY AS STUDENT COACHES FACİNG THE NATİONAL SCİENCE OLYMPİAD (OSN). Teacher training for National Science Olympiad (OSN) coaches is carried out as an effort to improve the professional competence of the Pasaman Regency Chemistry MGMP to prepare students to take part in competitions at the district and provincial levels. The ability of teachers prior to participating in the training was identified using pre-tests originating from OSN questions for the last five years. The training was carried out through analysis of OSN-K (City/District Level) and OSN-P (Provincial Level) questions for the last 5 years in 5 groups, and each group made written discussions which were compiled into modules that could be used by the trainees to prepare students in their respective schools. After that, discussions on HOTS questions in the fields of Inorganic Chemistry, Organic Chemistry, Physical Chemistry, Analytical Chemistry and Biochemistry were given by the resource persons. At the end of the activity, a final test is given to see the effectiveness of the training. The results of the pre-test and post-test showed an increase in participants' understanding of 23.51. In addition, the response to the activity evaluation questionnaire obtained an average questionnaire of 3.47 (scale 4), which means that the training is in the good category.

Stepwise Asymmetric Allylic Substitution‐Isomerization Enabled Mimetic Synthesis of Axially Chiral B,N‐Heterocycles

AbstractAxially chiral molecules bearing multiple stereogenic axes are of great importance in the field of organic chemistry. However, the efficient construction of atropisomers featuring two different types of stereogenic axes has rarely been explored. Herein, we report the novel atroposelective synthesis of configurationally stable axially chiral B,N‐heterocycles. By using stepwise asymmetric allylic substitution‐isomerization (AASI) strategy, diaxially chiral B,N‐heterocycles bearing B−C and C−N axes that are related to the moieties of axially chiral enamines and arylborons were also obtained. In this case, all four stereoisomers of diaxially chiral B,N‐heterocycles were stereodivergently afforded in high enantioselectivities. Density functional theory (DFT) studies demonstrated that the NH⋅⋅⋅π interactions played a unique role in the promotion of stereospecific isomerization, thereby leading to the highly efficient central‐to‐axial chirality transfer.

Stepwise Asymmetric Allylic Substitution-Isomerization Enabled Mimetic Synthesis of Axially Chiral B,N-Heterocycles.

Axially chiral molecules bearing multiple stereogenic axes are of great importance in the field of organic chemistry. However, the efficient construction of atropisomers featuring two different types of stereogenic axes has rarely been explored. Herein, we report the novel atroposelective synthesis of configurationally stable axially chiral B,N-heterocycles. By using stepwise asymmetric allylic substitution-isomerization (AASI) strategy, diaxially chiral B,N-heterocycles bearing B-C and C-N axes that are related to the moieties of axially chiral enamines and arylborons were also obtained. In this case, all four stereoisomers of diaxially chiral B,N-heterocycles were stereodivergently afforded in high enantioselectivities. Density functional theory (DFT) studies demonstrated that the NH⋅⋅⋅π interactions played a unique role in the promotion of stereospecific isomerization, thereby leading to the highly efficient central-to-axial chirality transfer.

Main group cyanides: from hydrogen cyanide to cyanido-complexes

Abstract Homoleptic cyanide compounds exist of almost all main group elements. While the alkali metals and alkaline earth metals form cyanide salts, the cyanides of the lighter main group elements occur mainly as covalent compounds. This review gives an overview of the status quo of main group element cyanides and cyanido complexes. Information about syntheses are included as well as applications, special substance properties, bond lengths, spectroscopic characteristics and computations. Cyanide chemistry is presented mainly from the field of inorganic chemistry, but aspects of chemical biology and astrophysics are also discussed in relation to cyano compounds.

Syntheses of Symmetrical and Unsymmetrical Lysobisphosphatidic Acid Derivatives.

Recent years have witnessed significant achievements in the field of organic chemistry, which have led to new drugs and the discovery of new and biologically interesting molecules. Herein, we describe a practical and efficient approach to the synthesis of enantiomerically pure and diverse lysobisphosphatidic acid analogues. The key feature of the synthesis is a one-pot, sequential phosphorylation of a protected sn-2-O-oleoyl glycerol or sn-3-O-oleoyl glycerol with 2-cyanoethyl N,N-diisopropylchlorophosphoramidite, followed by oxidation.

Mechanistic Investigation of the Nickel-Catalyzed Metathesis between Aryl Thioethers and Aryl Nitriles

Functional group metathesis is an emerging field in organic chemistry with promising synthetic applications. However, no complete mechanistic studies of these reactions have been reported to date, particularly regarding the nature of the key functional group transfer mechanism. Unraveling the mechanism of these transformations would not only allow for their further improvement but would also lead to the design of novel reactions. Herein, we describe our detailed mechanistic studies of the nickel-catalyzed functional group metathesis reaction between aryl methyl sulfides and aryl nitriles, combining experimental and computational results. These studies did not support a mechanism proceeding through reversible migratory insertion of the nitrile into a Ni-Ar bond and provided strong support for an alternative mechanism involving a key transmetalation step between two independently generated oxidative addition complexes. Extensive kinetic analysis, including rate law determination and Eyring analysis, indicated the oxidative addition complex of aryl nitrile as the resting state of the catalytic reaction. Depending on the concentration of aryl methyl sulfide, either the reductive elimination of aryl nitrile or the oxidative addition into the C(sp2)-S bond of aryl methyl sulfide is the turnover-limiting step of the reaction. NMR studies, including an unusual 31P-2H HMBC experiment using deuterium-labeled complexes, unambiguously demonstrated that the sulfide and cyanide groups exchange during the transmetalation step, rather than the two aryl moieties. In addition, Eyring and Hammett analyses of the transmetalation between two Ni(II) complexes revealed that this central step proceeds via an associative mechanism. Organometallic studies involving the synthesis, isolation, and characterization of all putative intermediates and possible deactivation complexes have further shed light on the reaction mechanism, including the identification of a key deactivation pathway, which has led to an improved catalytic protocol.

GNN-Retro: Retrosynthetic Planning with Graph Neural Networks

Retrosynthetic planning plays an important role in the field of organic chemistry, which could generate a synthetic route for the target product. The synthetic route is a series of reactions which are started from the available molecules. The most challenging problem in the generation of the synthetic route is the large search space of the candidate reactions. Estimating the cost of candidate reactions has been proved effectively to prune the search space, which could achieve a higher accuracy with the same search iteration. And the estimation of one reaction is comprised of the estimations of all its reactants. So, how to estimate the cost of these reactants will directly influence the quality of results. To get a better performance, we propose a new framework, named GNN-Retro, for retrosynthetic planning problem by combining graph neural networks(GNN) and the latest search algorithm. The structure of GNN in our framework could incorporate the information of neighboring molecules, which will improve the estimation accuracy of our framework. The experiments on the USPTO dataset show that our framework could outperform the state-of-the-art methods with a large margin under the same settings.

Biomolecular Chemical Simulations on Enantioselectivity and Reactivity of Lipase Enzymes to Azulene Derivatives

Biomolecular chemical simulations have recently become a useful research method in the fields of organic chemistry and bioscience. In the last few years, we have been focusing on the biomolecular computational simulation on lipase enzyme and ligand complexes to predict the enantioselectivity and reactivity of lipases toward non-natural organic compounds. In this paper, we describe the molecular simulations including molecular dynamics (MD) and fragment molecular orbital (FMO) calculations for the complexes of Candida antarctica lipase type A (CALA) and trifluoromethylazulene alcohol derivatives. From the MD calculations, we found that the fast-reacting enantiomer of esters with high enantioselectivity stays in the vicinity of the active site of CALA, while the slow-reacting enantiomer leaves the active site of CALA. On the other hand, both ( R)- and ( S)-enantiomers of ester with low ensntioselectivity were found to keep near to near the active site of CALA. Further, for the esters that do not react with lipase enzyme, we found that both ( R)- and ( S)-enantiomers move away from the active site of lipase enzyme. From the FMO calculations, we found that each fast-reacting enantiomer of esters with high enantioselectivity strongly interacts with certain particular amino acid residues in CALA containing Asp95, while both ( R)- and ( S)-enantiomers of ester with low enantioselectivity interact with same amino acid residues in CALA including Asp95. These results suggest that it is possible to predict not only the enantioselectivity but also the reactivity of CALA and to identify the amino acid residues important to the enzymatic reaction. Therefore, we consider that our computational simulations would be a useful method for predicting and understanding the reactivity and the enantioselectivity of lipase-catalyzed biotransformations.

Synthesis and characterization of tetraphenylammonium salts

The phenyl (Ph) group is a representative substituent in the field of organic chemistry as benzene (the parent molecule) is of fundamental importance. Simple Ph-substituted compounds of common chemical elements are well known. However, extensive structural characterization of tetraphenylammonium (Ph4N+) salts has not been reported. Herein, the synthesis of Ph4N+ salts and their characterization data including the 1H and 13C nuclear magnetic resonance (NMR) spectra and the single-crystal X-ray structure have been presented. An intermolecular radical coupling reaction between an aryl radical and a triarylammoniumyl radical cation was conducted to synthesize the target moieties. The Ph4N+ salts described herein are the simplest tetraarylammonium (Ar4N+) salts known. The results reported herein can potentially help access the otherwise inaccessible non-bridged Ar4N+ salts, a new class of rigid and sterically hindered organic cations.

Protonation-Induced Antiaromaticity in Octaaza[8]circulenes: Cyclooctatetraene Scaffolds Constrained with Four Amidine Moieties.

The switching of cyclic π-conjugation pathways using external stimuli is an attractive research topic in the field of organic chemistry. Here, we synthesized C4h -symmetric octaaza[8]circulenes with four peripherally arranged amidine moieties that exhibit enhanced antiaromaticity upon protonation. Titration experiments with methanesulfonic acid revealed the formation of the tetraprotonated forms of the octaaza[8]circulenes in solution. Single-crystal X-ray diffraction analyses and theoretical calculations indicated that the contribution of the 8π antiaromatic character of the octaaza[8]circulenes is enhanced by the delocalization of charge through the protonation of the pyridine rings.

The Rise of 1,4-BN-Heteroarenes: Synthesis, Properties, and Applications.

BN‐heteroarenes, which employ both boron and nitrogen in aromatic hydrocarbons, have gained great attention in the fields of organic chemistry and materials science. Nevertheless, the extensive studies on BN‐heteroarenes are largely limited to 1,2‐azaborine‐based compounds with B–N covalent bonds, whereas 1,3‐ and 1,4‐BN‐heteroarenes are relatively rare due to their greater challenge in the synthesis. Recently, significant progresses have been achieved in the synthesis and applications of BN‐heteroarenes featuring 1,4‐azaborines, especially driven by their significant potential as multiresonant thermally activated delayed fluorescence (MR‐TADF) materials. Therefore, it is timely to review these advances from the chemistry perspective. This review summarizes the synthetic methods and recent achievements of 1,4‐azaborine‐based BN‐heteroarenes and discusses their unique properties and potential applications of this emerging class of materials, highlighting the value of 1,4‐BN‐heteroarenes beyond MR‐TADF materials. It is hoped that this review would stimulate the conversation and cooperation between chemists who are interested in azaborine chemistry and materials scientists working in the fields of organic optoelectronics, metal catalysis, and carbon‐based nanoscience etc.

Intersection of Inorganic Chemistry and Nanotechnology for the Creation of New Cancer Therapies.

Since its discovery in 1965, the inorganic drug cisplatin has become a mainstay of cancer therapies and has inspired many platinum (Pt)-based compounds to solve various issues of toxicity and limitations associated with the original cisplatin. However, many of these drugs/prodrugs continue to be plagued by an array of side effects, limited circulation, and half-life and off-target effects. To solve this issue, we have constructed an array of platinum-based prodrugs on a Pt(IV) skeleton, which provides more favorable geometry and hydrophobicity, easier functionalization, and ultimately better targeting abilities. Each of these Pt(IV) prodrugs aims to either combine cisplatin with other agents for a combination therapeutic effect or improve the targeting of cisplatin itself, all for the more effective treatment of specific cancers. Our developed prodrugs include Platin-A, which combines cisplatin with the anti-inflammatory agent aspirin, Platin-M, which is functionalized with a mitochondria-targeting moiety, and Platin-B and Platin-Cbl, which combine cisplatin with components to combat cellular resistance to chemotherapy. At the same time, however, we recognize the crucial role of nanotechnology in improving the efficacy of cisplatin prodrugs and other inorganic compounds for the treatment of cancers. We describe several key benefits provided by nanomedicine that vastly improve the reach and utility of cisplatin prodrugs, including the ability of biodegradable polymeric nanoparticles (NPs) to deliver these agents with precision to the mitochondria, transport drugs across the blood-brain barrier, and target cisplatin prodrugs to specific cancers using various ligands. In addition, we highlight our progress in the engineering of innovative new polymers to improve the release patterns, pharmacokinetics, and dosages of cancer therapies. In this Account, we aim to describe the growing need for collaboration between the fields of inorganic chemistry and nanotechnology and how new advancements can not only improve on traditional chemotherapeutic agents but also expand their reach to entirely new subsets of cancers. In addition to detailing the design and principles behind our modifications of cisplatin and the efficacy of these new prodrugs against aggressive, cisplatin-resistant, or metastatic cancers, we also shed light on nanotechnology's essential role in protecting inorganic drugs and the human body from one another for more effective disease treatment without the off-target effects with which it is normally associated. We hope that this perspective into the important intersection between inorganic medicinal chemistry and nanotechnology will inspire future research on cisplatin prodrugs and other inorganic agents, innovative polymer and NP design, and the ways in which these two fields can greatly advance cancer treatment.

Copper‐Mediated and Catalyzed C—H Bond Amination via Chelation Assistance: Scope, Mechanism and Synthetic Applications

Comprehensive SummaryNitrogen‐containing compounds are ubiquitously found in the fields of organic chemistry, pharmaceuticals, agrochemicals, medicinal chemistry and functional materials. The C—H bond amination reaction is one of the most straightforward protocols in the C—N bond formation, showing "step" and "atomic" economy. As a catalyst for C—H amination reaction, copper exhibits its unique catalytic properties due to easily accessible oxidation states. The research progress of copper‐catalyzed C—H amination in recent years is summarized. At the same time, reaction mechanisms are also briefly described in representative aminations to provide insights for the development prospects of highly practical and more environmentally benign processes.

Reusable Nano Catalysed Synthesis of Heterocycles: An Overview

AbstractThe field of reusable nano‐catalysts has grown rapidly over the last decade. Recently, transition metal catalysed organic reactions have attracted considerable interest from the pharmaceutical and organic chemistry fields. Synthetic procedures based on such heterogeneous nanocatalysts are easier, less expensive, non‐toxic, and eco‐friendly, producing only the most desirable products in higher yields and allowing for easy catalyst separation. Heterogeneous nano‐catalysts were highly preferred over homogeneous catalysts for the synthesis of heterocyclic compounds due to their effective separation processes for both products and catalysts. According to recent studies, nanoparticles (NPs) are commonly used as a heterogeneous catalyst in the production of heterocyclic compounds. Heterogeneous catalysts are widely used in a variety of organic reactions due to their high surface‐to‐volume ratio. Most importantly, after the reaction is complete, easy magnetic separation of the catalyst minimises the requirement for catalyst filtration. Additionally, magnetic NPs, particularly supported magnetic nanocatalysts, have garnered considerable interest in both academic and industrial research due to their effectiveness as alternatives to traditional materials, their ease of separation via an external magnet, and their high degree of chemical stability in a variety of organic and inorganic solvents. To reach its depth, this review is focused on the most recent examples, their preparation, synthetic strategies and recycling studies of highly excited catalytic systems used for the synthesis of heterocyclic compounds.

COLOUR TERMS IN INORGANIC CHEMISTRY: A CORPUS STUDY

Colour is a common physical phenomenon involving selective absorption, reflection or transmission of certain wavelengths of light. It is one of the fundamental properties of chemical compounds, which is particularly evident in the field of inorganic chemistry. The aim of this paper is to present colour terms used by scientists in the field of inorganic chemistry. We concentrate both on basic and non-basic colour terms – as understood by Berlin and Kay (1969). The research material is extracted from a corpus compiled with AntConc, consisting of abstracts published in Inorganic Chimica Acta, Inorganic Chemistry Communications, Journal of Inorganic Biochemistry and ten other chemical journals. The size of the corpus is 1,626,380 words. The most frequent basic colour terms found in the abstracts are blue (370 occurrences), green (302) and red (222), whereas the non-basic terms include, among others, violet (46) and cyan (4). In this paper, we investigate the uses of these and other colour words, focusing mainly on their occurrence in names of chemical compounds and other terms as well as in descriptions.

Unapređivanje hemijske pismenosti učenika osnovnih škola kroz kontekstualni pristup obradi nastavne jedinice Alkani

Organic chemistry represents an essential part of everyday life, but previous research indicates that traditional organic chemistry teaching, which focuses on the transmission of academic content, insufficiently promotes the development of pupils' chemical literacy in this field. Since context-based teaching approach has the potential to improve scientific literacy, in order to compare the effectiveness of the aforementioned teaching approaches in terms of developing elementary school pupils' chemical literacy in the field of organic chemistry, a pedagogical experiment with parallel groups was conducted. The experiment was organized within the elaboration of the teaching unit Alkanes and it encompassed 148 eighth-grade elementary school pupils (76 pupils in the experimental and 72 pupils in the control group). Through the elaboration of the content about alkanes, pupils develop chemical literacy in regard to the structure and nomenclature of these compounds, their physical and chemical properties and oil and its derivatives as energy sources, as well as environmental pollutants. Upon the elaboration of the abovementioned teaching unit, the experimental group achieved a significantly higher overall percentage of correct answers on the test that checked the development of pupils' chemical literacy in regard to alkanes on all three levels (knowledge, application and reasoning), which implies that context-based teaching approach could significantly enhance elementary school pupils' chemical literacy, in the field of organic chemistry.

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Time to Celebrate

Molecular electrostatic potential as a general and versatile indicator for electronic substituent effects: statistical analysis and applications.

It is necessary to quantitatively determine substituent effects to accurately elucidate reaction mechanisms in the field of organic chemistry. This paper reports that the molecular electrostatic potential (MESP) can be used as a general and versatile measure for the substituent effects in various chemical reactions by performing extensive density functional theory (DFT) calculations for more than 400 molecules, followed by statistical analyses. We observed a robust and linear correlation between the electrostatic potential and the substituent parameters for various cases of reactive systems, regardless of the DFT functionals, basis sets, and solvation models used. In addition, we statistically analysed the normality of the residuals from the linear regression to demonstrate that strong linear relationships hold universally, which indicates that the electrostatic potential can serve as a physically meaningful quantity for the predictive estimation of substituent effects. In contrast, conventionally used methods based on the charge deviation in the aromatic carbons, as computed using various charge analysis methods, (e.g., Hirshfeld charge analysis) do not demonstrate the statistical normality. Furthermore, we illustrate that MESP can be extensively adopted to strengthen the validity of the linear free energy relationships (LFERs) under various chemical conditions. The results revealed that the MESP shift derived by a functional group on a mono-substituted benzene ring is a strong predictor for the substituent effects on the electronic behaviours in chemical reactions; thus, it can serve as an alternative to other empirical parameters such as the Hammett or Swain-Lupton parameters, or the charge shift.

Schiff-bases for sustainable battery and supercapacitor electrodes.

The quest for more efficient ways to store electrical energy prompted the development of different storage devices over the last decades. This includes but is not limited to different battery concepts and supercapacitors. However, modern batteries rely on electrochemical principles that often involve transition metals which can for instance suffer from toxicity or limited availability. More sustainable alternatives are needed. This sparked the search for organic electrode materials. Nevertheless, compared to their inorganic counterparts, organic electrode materials remain less intensely investigated. Besides the often more complicated electrochemical principles, one likely reason for that are the complex synthetic skills required to develop novel organic materials. Here we review materials synthesized by an old and comparably simple reaction from the field of organic chemistry, namely Schiff-base formation. This reaction can often yield materials under relatively mild conditions, making them especially interesting for the formation of sustainable electrodes. The main weakness of Schiff-base materials, susceptibility to hydrolysis, is of limited concern in most of the battery systems as they mostly anyways require water-free conditions. This review gives an overview of some selected nanomaterials obtained from Schiff-base formation as well as their carbonized derivatives which are of interest for energy storage. Firstly, the general chemistry of Schiff-bases is introduced, followed by an in-depth survey of the most important breakthroughs in the formation of organic battery electrodes that involve materials based on Schiff-base reaction. Lastly, an outlook considering the main hurdles as well as future perspectives of this research area is given.