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Chiral carboxylic acids bearing an α-stereogenic center constitute the backbone of many natural products and therapeutic reagents as well as privileged chiral ligands and catalysts. Hence, it is not surprising that a large number of elegant catalytic asymmetric strategies have been developed toward the efficient synthesis of α-chiral carboxylic acids, such as α-hydroxy acids and α-amino acids. In this review, the recent advances on asymmetric synthesis of α-stereogenic free carboxylic acids via organocatalysis and transition metal catalysis are summarized (mainly from 2010 to 2020). The content is organized by reaction type of the carboxyl source involved, including asymmetric functionalization of substituted carboxylic acids, cyclic anhydrides, α-keto acids and substituted α,β-unsaturated acids and so on. We hope that this review will motivate further interest on catalytic asymmetric synthesis of chiral α-substituted carboxylic acids.

Sulfinic acids and their salts are a useful source of sulfur-containing structures. Photocatalysis of these compounds with visible light enables to achieve various transformations under mild conditions. This review summarizes visible-light-induced reactions of sulfinic acids and their salts. It is organized by reaction type and brief discussions on plausible reaction mechanisms for typical transformations are presented.1 Introduction2 Sulfonylation Reactions2.1 Sulfonylation of Alkenes2.2 Sulfonylation of Alkynes2.3 Sulfonylation of Arenes2.4 sp3 C–H Functionalization3 Desulfonylation Reactions4 Sulfenylation Reactions4.1 Sulfenylation of Heteroarenes4.2 Sulfenylation of Carbonyl Chlorides5 Conclusions

Time to maximum rate under adiabatic condition (TMRad) and the corresponding initial temperatures such as TD24 (the initial temperature when TMRad equals 24 h) are essential parameters to evaluate thermal hazard of chemical process. The standard methods of calculating TMRad are based on the Nth-order model. To clarify the influence of the reaction type on TMRad, the heating-waiting-seeking (HWS) processes and the direct adiabatic process were simulated by numerical calculation according to a given kinetic parameters and adiabatic temperature rise (ΔTad). The relationship between TMRad and temperature (T) and its corresponding TD24 were obtained by using two standard methods for single step, two-steps parallel and continuous reactions. The calculation results show that: for single-step reaction, if it only involves Nth-order reaction, the deviation of TD24 is within 18 °C; if it involves autocatalytic reaction, the deviation of TD24 reaches to 300 °C under the calculation condition; the evaluation is not reliable and more risky at low temperature. The two-step reaction produced similar results. It can be judged that the standard methods are only applicable to the estimation of TMRad of Nth-order reactions. For the reactions involving autocatalysis, the method of co-fitting of multiple kinds of experimental data can be used with the help of analysis software.

Students perceive organic chemistry as a challenging subject for them to learn and master, which results in a high failure rate. This study investigates the perception of chemistry students of the Department of Chemistry, Kulliyyah of Science at International Islamic University Malaysia (IIUM), on organic chemistry courses and identify the topics that the students found difficult to grasp, which may affect their grades. The correlation of students’ perception on the difficulty level in studying organic chemistry subjects (I and II) with the grades obtained for both courses, and the correlation of the type of study attitude with the grades achieved for Organic Chemistry I and II, were also investigated. From the data analysis of questionnaires distributed to 160 respondents, stereochemistry (n = 58.8 %), determination of reaction type (n = 59.4 %), construction of the reaction mechanisms (n = 73.2 %), and characterisation of organic reaction (n = 77.5 %), were the topics that the students perceived to be difficult. Perception on the difficulty in studying organic chemistry was positively associated with the achievement of excellent grades for both organic chemistry subjects (I; rs = 0.413**, p

Background Where an ongoing requirement for intravenous iron replacement exists after an index infusion reaction, current recommendations are limited to expert opinion and isolated case reports. Objective To evaluate the safety of recommencing an infusion or subsequent rechallenge following an infusion reaction to intravenous iron. Methods Infusion reactions to intravenous iron occurring between January 1, 2010, and December 31, 2019, at a metropolitan health network were identified. Patient characteristics, reaction type (mild, moderate, or severe hypersensitivity, delayed, or Fishbane: transient flushing and truncal myalgias), and outcomes of recommencing the index infusion or subsequent rechallenge were examined. Results Among 13,509 iron infusions, 195 infusion reactions occurred in 195 patients (1.4% of infusions). Recommencement of the index infusion (generally with a reduced infusion rate and premedication) was tolerated in 33 of 33 patients with Fishbane (20 of 20) or mild (9 of 9) and moderate (4 of 4) hypersensitivity reactions. Subsequent rechallenge (generally at standard infusion rates to an alternative formulation, ferric carboxymaltose) was successful in 68 of 69 patients with Fishbane (23 of 23), mild (26 of 26), moderate (16 of 17), and severe (3 of 3) hypersensitivity, or delayed (2 of 2) reactions. All 9 patients rechallenged to the original formulation (iron polymaltose) completed the infusion. Conclusions Following an infusion reaction to intravenous iron infusion, recommencement of the index infusion is safe for Fishbane or mild and moderate hypersensitivity reactions. Subsequent rechallenge to an alternative formulation is tolerated, including in severe hypersensitivity reactions (albeit based on limited numbers). Where alternative formulations are not available, rechallenge to the same formulation could be considered, depending on the risk-benefit profile.

Azetidines represent one of the most important four-membered heterocycles used in organic synthesis and medicinal chemistry. The reactivity of azetidines is driven by a considerable ring strain, while at the same the ring is significantly more stable than that of related aziridines, which translates into both facile handling and unique reactivity that can be triggered under appropriate reaction conditions. Recently, remarkable advances in the chemistry and reactivity of azetidines have been reported. In this review, we provide an overview of the synthesis, reactivity and application of azetidines that have been published in the last years with a focus on the most recent advances, trends and future directions. The review is organized by the methods of synthesis of azetidines and the reaction type used for functionalization of azetidines. Finally, recent examples of using azetidines as motifs in drug discovery, polymerization and chiral templates are discussed.

The direct use structurally simple ketones as α-ketone radical sources for α-C(sp3)–H functionalization is a sustainable and powerful approach for constructing complex and multifunctional chemical scaffolds with diverse applications. The reactions of α-ketone radicals with alkenes, alkynes, enynes, imides, and imidazo[1,2-a]pyridines have broadened the structural diversity and complexity of ketones. Through chosen illustrative examples, we outline the recent progress in the development of methods that enable the radical α-C(sp3)–H functionalization of ketones, with an emphasis on radical initiation systems and possible mechanisms of the transformations. The application of these strategies is illustrated by the synthesis of several biologically active molecules and drug molecules. Further subdivision is based on substrate type and reaction type.

Subject of Research. The paper presents a study of prediction method for various properties of reactions, such as the type of reaction, suitable groups of solvents, catalysts for the reaction. Molecular fingerprint differences between products and reagents were calculated using the RdKit chemical library as a representation of the reactions. Molecular fingerprints are widely used to predict various properties of molecules. Knowledge of the reaction conditions is essential for successful planning of retrosynthesis. Chemical informatics methods can effectively find the relationship between reaction reagents and the necessary conditions for the reaction. At this, the costs of time and resources spent on the determination of the necessary set of conditions for the reaction are reduced. Prediction of solvent groups can significantly improve the quality of models and the applicability of approaches. Method. LightGBM and a neural network with Deep Feature Selection were taken as machine learning models. The results were evaluated with the F1-metric. For the models training and evaluation, the data was broken down into chemically dissimilar parts. Bayesian optimization was used to optimize the searching of parameters. Main Results. Experiments were carried out to predict the reaction type, catalysts and solvent groups for the reaction. The obtained results show that the MLP type of reaction can be predicted equal to 0.99, a MLP catalyst equal to 0.7, and MLP group of solvents equal to 0.68 with F1-metric based on the difference in molecular fingerprints between reagents and products of machine learning models. Significant quantity of catalysts and solvents are considered in the paper. Practical Relevance. Automated planning of retrosynthesis is one of the topical areas of research. During planning, a sequence of necessary reactions is drawn up. The considered method can be used for recommendation system development that can suggest a possible group of catalysts and solvents to a chemical specialist, and, thus, reduce the cost of resources and time to determine the necessary reaction conditions.

Determination of the budget and regional expenditure income (APBD) of Kuantan Singingi Regency has a polemic in the formulation process. The delay in the enactment of this regional budget regulation indicates that there is a bad relationship between the regional head and the Kuantan Singingi district parliament. To answer the problems that occur, an analysis is conducted to find the bright spots of the polemic. This research was conducted to see the relationship between the DPRD and local government in the process of formulating the APBD. This research uses a qualitative approach. Data collection techniques namely by studying literature and using previous research. This study uses Stone's interaction type theory, namely decisional type, anticipated reaction type, non-decisional making type, systemic type. The results showed that the relationship between the local government and the Regional Parliament of Kuantan Singingi in the formulation of the 2017 Regional Budget was included in the type of non-decessional making interaction. This type of interaction is a form of interaction that is influenced by the presence of a strong majority group in influencing the process of formulating the APBD, especially on the submission and agreement of the KUA-PPAS by providing public issues so that a bad image is formed.

An unparalleled [4 + 2]-annulation of prop-2-ynylsulfonium salts with isatoic anhydrides was developed, affording a series of 4-quinolones with a alkylthio group in medium to good yields under mild conditions. In this reaction type, the prop-2-ynylsulfonium salt serves as a C2 synthon and sulfide does not act as a leaving group, providing facile access to organosulfur compounds. The resulting quinolone products could be further transformed to a diverse range of synthetically useful compounds.

Polyketide natural products are an important class of biologically active compounds. Although substantial progress has been made on the synthesis of repetitive polyketide motifs through the iterative application of a single reaction type, synthetic access to more diverse motifs that require more than one type of carbon-carbon bond connection remains a challenge. Here we describe a catalytic, multicomponent method for the synthesis of the privileged polyketide 1,3-dienyl-6-oxy motif. The method allows for the formation of two new carbon-carbon bonds and two stereodefined olefins. It generates products that contain up to three contiguous sp3 stereocentres with a high stereoselectivity in a single operation and can be used to generate chiral products. The successful development of this methodology relies on the remarkable efficiency of the ruthenium-catalysed alkene-alkyne coupling reaction between readily available vinyl boronic acids and alkynes to provide unsymmetrical 3-boryl-1,4-diene reagents. In the presence of carbonyl compounds, these reagents undergo highly diastereoselective allylations to afford the desired 1,3-dienyl-6-oxy motif and enable complex polyketide synthesis in a rapid and asymmetric fashion.

Tertiary enamides display versatile reactivity and great stability compared to their enamine congeners. This review covers progress made in the development of new methods involving the enaminic reactivity of tertiary enamides with respect to the synthesis of complex nitrogen-containing compounds. A focus on the preparation of biologically active molecules is also presented. The syntheses reported herein are classified based on their reaction type. In addition, mechanistic insights are given for most of the new transformations.1 Introduction2 [2+2] Cycloadditions3 [4+2] Cycloadditions4 Electrocyclizations and Cycloisomerizations5 Sigmatropic Rearrangements6 Nucleophilic Additions7 Tertiary Enamides as Electrophiles8 Cross-Coupling Reactions9 Tertiary-Enamide-Assisted Reactions10 Conclusion and Perspectives

Cyclization between two multiple bonds have been attractive processes that allow the discovery of novel reactions and the construction of carbo- and/or heterocycles. Among them, heteroatom-substituted unsaturated bonds show different reactivity from those with a heteroatom displaced on the α- or β-carbon, but surprisingly few reactions using them have been reported until the 2000s. In recent years, benzo-fused substrates cyclization between two multiple bonds, including heteroatom-substituted unsaturated bonds, have been reported, and this review describes them by reaction type.

Four-component reactions of 3-amino-1,2,4-triazole or 5-amino-1H-pyrazole-4-carbonitrile with aromatic aldehydes and pyruvic acid or its esters under ultrasonication were studied. Unusual for such a reaction type, a cascade of elementary stages led to the formation of 7-azolylaminotetrahydroazolo[1,5-a]pyrimidines.

This paper deals with a two-chemical reaction type Keller-Segel system coupled with incompressible viscous fluid equations which models the dynamics of cells in fluid in a two dimensional bounded domain $\varOmega $ $$ \left\{ \textstyle\begin{array}{l} \partial _{t}n+\mathbf {u}\cdot \nabla n = \Delta n - \nabla \cdot \bigl(n\chi(n,v,w,x)\nabla v\bigr), \\ \partial _{t}v+\mathbf {u}\cdot \nabla v= \Delta v -v + w, \\ \partial _{t}w+\mathbf {u}\cdot \nabla w = \Delta w -w + n, \\ \partial _{t}\mathbf {u}+ \nabla P = \Delta \mathbf {u}+ n\nabla \psi, \quad \nabla \cdot \mathbf {u}= 0. \end{array}\displaystyle \right. $$ Here, $\chi(n,v,w,x)$ represents the saturated sensitivity. Our result suggests that suitable saturation can prevent the blow-up arising from the classical Keller-Segel type signal production mechanism without any smallness condition on initial mass.

Over the past 20 years reports of sulfonyl migrations have appeared, frequently described as ‘unusual’ and ‘unexpected’. This comprehensive review compiles, for the first time, sulfonyl migrations reported over the last 20 years including formal 1,2-, 1,3-, 1,4-, 1,5-, 1,6- and 1,7-sulfonyl shifts, occurring through either radical or polar processes, either inter- or intramolecularly. Discussion of the sulfonyl migrations is structured according to reaction type, i.e. nitrogen–carbon, nitrogen–oxygen, nitrogen–nitrogen, oxygen–carbon (including anionic and non-anionic thia-Fries rearrangements), oxygen–oxygen and carbon–carbon migrations. Discussion of the underlying mechanisms for the migrations is included, with particular attention afforded to the principal techniques utilised for their elucidation, namely isotopic-labelling, crossover experiments, density functional theory calculations and electron paramagnetic resonance spectroscopy amongst others.

Human body produces different physiological stress reaction when you hit a toe to a doorstep than when you panic at a job interview. The impact for body's homeostasis varies depending on the reaction type and some reactions are harmful to our health. Currently, stress estimation is focused on binary identification between stress and non-stress stages. More detailed separation of stress reaction types is needed for detecting harmful stress. In this study, the Extreme Gradient Boosting algorithm was used to classify a baseline condition and physiological and psychosocial stress, based on psychophysiological signals monitored using a wrist sensor device. Classification was robust in separating the two stress states from baseline and from each other. The results provide support for novel approaches utilizing fine-grained estimation of stress type from wearable sensor data.

Hymenoptera species include stinging insects such as wasps, hornets, bees, and fire ants. Allergic reaction to the venom of these insects is a common presenting complaint for patients in primary care and emergency medicine during warmer months. Patients' clinical presentations may vary, and clinicians must identify the type of reaction to determine treatment and follow-up plans. Treatment of patients allergic to Hymenoptera venom should be individualized based on risk factors, reaction type, and associated comorbidities. This article reviews common features of clinical presentation, diagnosis, and the current mainstays in management of Hymenoptera venom allergy.

BACKGROUND & OBJECTIVES Serologic testing after transfusion reactions (TRs) aims to find accountable immune haemolytic incompatibility. Our hospital policies recommend serologic testing in all TR, except for low-risk fevers (subclinical temperature

The inverse electron demand Diels-Alder conjugation reaction has gained increasing importance over the past few years for efficient in vivo and ex vivo radiometal labeling of antibodies. However, the application of this very fast reaction type has not been studied for radiolabeling of peptides so far. We show here the synthesis of 3-benzyl-1,2,4,5-tetrazine-comprising ((1,4,7,10-tetraazacyclododecane-4,7,10-triyl)triacetic acid-1-glutaric acid) (DOTA-GA) and ((1,4,7-triazacyclononane-4,7-diyl)diacetic acid-1-glutaric acid) (NODA-GA) chelators and their radiometal labeling with 68Ga3+ and 64Cu2+. The secondary labeling precursors 68Ga-DOTA-GA-Tz, 68Ga-NODA-GA-Tz, and 64Cu-DOTA-GA-Tz were obtained in high radiochemical yields (RCYs) and purities as well as molar activities for further labeling of trans-cyclooctene (TCO)-modified peptides. However, the following reactions of the radiometal-labeled tetrazines with different TCO-comprising model peptide analogs unexpectedly resulted in the formation of a considerable amount of side products (20-55%) which limits the overall achievable RCYs and purities as well as molar activities of the target radiopeptides. Under otherwise identical, nonradioactive reaction conditions, this effect could however not be observed. In contrast, the corresponding one-step radiolabeling protocols provided the target 68Ga-labeled radiopeptides in exceptionally high RCYs and purities of ≥99% and molar activities of 68-72 GBq/μmol starting from activities of 340-358 MBq of 68Ga. Thus, the usefulness of the two-step labeling of TCO-modified peptides with radiometal-labeled chelator-tetrazines seems to be limited.

Chlorine dioxide has been widely used as an internationally recognized safe and non-toxic green disinfectant. Chlorine dioxide has been listed as an A1 disinfectant by the United Nations Health Organization (WHO). Its strong oxidation can achieve sterilization, disinfection, preservation and other effects and is widely used. Compared with liquid chlorine dioxide, solid chlorine dioxide preparations have the advantages of high stability, easy to transport and so on, and have a wider application range. In this paper, the research status of solid chlorine dioxide in recent years is summarized into reaction type and adsorption type. Most solid preparations also have disadvantages such as difficulty in controlling the release rate and insufficient release time. Among them, the gel-type sustained-release agent can improve these shortcomings and provide a reference for the future development of chlorine dioxide solid preparations.

This review article summarizes the applications of nickel(II) compounds in organic synthesis since 2016. In recent years, the field of nickel(II) catalysis is gaining considerable interest due to readily available, low-cost nickel(II)-compounds and several key properties of nickel. This review article is organized by the reaction type, although some reactions can be placed in multiple sections.

Catalytic kinetic resolution is often the "method of choice" for the preparation of optically enriched functionalized compounds and, over the past decade, kinetic resolutions and dynamic kinetic resolutions catalyzed by N-heterocyclic carbenes (NHCs) have been employed for the synthesis of a variety of optically enriched functionalized molecules. Herein we provide an overview of reported NHC-catalyzed kinetic resolutions in terms of the structure of the substrate, the reaction type, and the activation mode. This Focus Review is arranged according to the structure of the racemic compounds and includes the kinetic resolution of alcohols, amines, imines, and aldehydes, as well as dynamic kinetic resolution. In each section, the activation mode and reaction mechanism are discussed. We conclude with a summary of the current state-of-play in NHC-catalyzed kinetic resolution and provide an outlook for the development of this field in the future.

Monofluoroalkenes have found wide application in organic chemistry, medicinal chemistry, and materials science. This review summarizes the most recent advances made regarding the preparation of monofluoroalkenes, covering the period between October 2010 and September 2017. This review is divided in three main parts, one for each possible substitution pattern, namely di-, tri-, and tetrasubstituted. Then, for each class, further subclassification is made according to the reaction type.1 Introduction2 Disubstituted Monofluoroalkenes2.1 Disubstituted α-Monofluoroalkenes2.2 Disubstituted β-Monofluoroalkenes3 Trisubstituted Monofluoroalkenes4 Tetrasubstituted Monofluoroalkenes5 Conclusions

Reversible bimolecular chemical reactions are elementary chemical reactions. This paper investigated this reaction type based on DNA strand displacement, and proposed degradation, catalysis, and annihilation reactions along with the synchronization reaction modules. DNA reaction modules were compared with ideal reaction modules, and relative reaction rates analyzed using the Lotka–Volterra oscillator as an example to demonstrate the validity of these reaction modules. An arbitrary chemical reaction network was employed to numerically simulate and predict synchronization between two Lotka–Volterra oscillators.

Fly ash is the main waste generated from coal production. The application of fly ash in building materials helps reduce pollution. In the present work, a novel reaction-type nucleation seed accelerator with D50 of 512 nm was prepared from coal fly ash using wet-grinding technology, denoted as WFA seed. The physical and chemical performances of WFA seed and its promotion effect on hydration, strength and microstructure of Portland cement (PC) were studied. With the addition of WFA seed, compressive strength was significantly increased by 50% and 16% at 12 h and 28 days. The hydration heat peak was also clearly increased by WFA seed. The hydration and strength promotion by WFA seed is attributed to the dual function of secondary reaction (which occurs as early as 12 h) and nucleation induction, which is different from the single function of nucleation site effect of some existing nano-materials. Furthermore, the main chain length and Al/Si ratio of C-S-H gel were increased, and the pore structure of cement was refined by the addition of WFA seed.

The first example of the SN2′ reaction type of the detrifluoroacetylatively in situ generated tertiary fluoro-enolates in the uncatalyzed reactions with Morita–Baylis–Hillman derivatives has been described. The SN2′ substitution takes place in a highly chemoselective manner as no corresponding SN2 products were observed in the reaction mixtures. Due to the excellent stereochemical outcome, the reactions seem to have an apparent synthetic value for the preparation of structurally new fluorinated oxindoles.

Background. This article reveals the importance of studying the problem of success in foreign language acquisition during the rst stage of study in the modern educational environment. Particular attention is paid to factors of successful foreign language acquisition during the primary-school ages, which depends on cognitive style features, such as reaction type and cognitive control. e content and characteristics of cognitive styles as individual styles of foreign language acquisition are analyzed in the context of a leading activity of primary school students. Objective. A hypothesis of this research was that success in foreign language acquisition depends on reaction type and cognitive control, particularly the extent of the cognitive styles of impulsivity, re exivity, rigidity and exibility in primary-school students. Design. To implement the proposed empirical tasks, the author organized and conducted research using a combination of methods intended to study the correlation between success in foreign language acquisition by primary-school students and reaction type as well as the features of cognitive control. A total of 74 elementary-school pupils aged 8-11 years were studied. A direct connection between success in foreign language acquisition and the indicators of the cognitive style “impulsivity — re exivity” was iden- ti ed using mathematical statistics methods. Results. This study found no statistically signi cant correlation between success in foreign language acquisition and the indicators of the cognitive style “rigidity — exibility”. erefore, the results con rm that success in foreign language acquisition at prima- ry-school ages is determined more by reaction type (impulsive or re exive) than by the features of cognitive control (rigidity or exibility). Conclusion: The practical significance of the study is that the obtained results can be used in the work of teachers and psychologists to improve the educational process in primary school and to promote the e ective study of foreign language by students.

3D computer models of Fe–Ni–Co, Fe–Ni–FeS–NiS, Fe–Co–FeS–CoS, Ni–Co–NiS–CoS T–x–y diagrams have been designed. The geometric structure (35 surfaces, two-phase surface of the reaction type change, 17 phase regions) of the Fe–Ni–FeS–NiS T–x–y diagram is investigated in detail. The liquidus hypersurfaces prediction of the Fe–Ni–Co–FeS–NiS–CoS subsystem is represented.

Retrosynthesis prediction is a crucial task for organic synthesis. In this work, we propose a single-step template-free and Transformer-based method dubbed RetroPrime, integrating chemists’ retrosynthetic strategy of (1) decomposing a molecule into synthons then (2) generating reactants by attaching leaving groups. These two stages are accomplished with versatile Transformer models, respectively. RetroPrime achieves the Top-1 accuracy of 64.8% and 51.4%, when the reaction type is known and unknown, respectively, in the USPTO-50 K dataset. And the Top-1 accuracy is close to the state-of-the-art transformer-based method in the large dataset USPTO-full. It is known that outputs of the Transformer-based retrosynthesis model tend to suffer from insufficient diversity and high chemical implausibility. These problems may limit the potential of Transformer-based methods in real practice, yet few works address both issues simultaneously. RetroPrime is designed to tackle these challenges.

Gas-liquid reactions represent an important and popular reaction type in chemical industry. On this account, the understanding of ongoing mass transport processes is of high importance. Nevertheless, there is still insufficient information on the interaction between mass transfer and chemical reaction, mainly due to the problem of decoupling mass transfer and reaction. To tackle this challenge, the possibility of decoupling these processes is introduced by use of photochemical reactions as switchable reactions. The feasibility of this concept is demonstrated by taking the photochlorination of toluene as an example. Experimental results show that the aimed separation of mass transfer and reaction can be achieved, providing an innovative tool for the investigation of mass transfer processes.

The 2-arylcyclopropylamine (ACPA) motif is often seen in biologically active compounds. This review focuses on the synthesis of biologically active ACPAs and categorizes, by reaction type, the synthetic methods used toward such compounds. 1 Introduction 2 Cyclopropanation Using Diazo Compounds 2.1 Styrene 2.2 Cinnamate 2.3 Vinyl Phthalimide 2.4 Vinyl Acetamide 2.5 Oxazolone 2.6 Diketopiperazine 3 Cyclopropanation Using Ylides 3.1 Cinnamate 3.2 Nitrostyrene 3.3 Oxirane 3.4 Nitroacetate 4 Transformation of Cyclopropanes 4.1 Iodocyclopropane 4.2 Aminocyclopropane 5 Miscellaneous Methods 5.1 Kulinkovich Reaction 5.2 Three-Component Reaction 5.3 Intramolecular Nucleophilic Cyclization 5.4 Intramolecular Mitsunobu Reaction 5.5 Rearrangement from Cyclobutanone 6 Summary

An unexpected FeCl3-promoted reaction of cyclic imine dibenzo[b,f][1,4]oxazepines with alkynes was studied, leading to a series of 4-substituted 3-(2-hydroxyphenyl)-quinolines. A variety of substituted cyclic imines and terminal alkynes (arylacetylenes, conjugated enynes, and 1,3-diynes) were used for this reaction type resulting in the formation of the corresponding products in yields ranging from 34 to 88%. A reasonable reaction mechanism involving a tandem reaction procedure was proposed on the basis of control experiments. The reaction sequence demonstrated herein represents an efficient, yet practical method for the synthesis of novel 4-substituted 3-(2-hydroxyphenyl)-quinoline derivatives.

Cognitive styles defined as the way by which individuals prefer to use in order to obtain, edit, utilize, remember the information are discussed as the indication of individual differences in many studies. The study aims to investigate behavioral data of mathematics teacher candidates categorized according to their cognitive styles while they perform subtraction operations with small and big numbers. Participants of the study were 30 teacher candidates, 15 of whom have field-dependent cognitive style while 15 of whom have field-independent cognitive style. Obtained data was analyzed in terms of accuracy and reaction time according to the cognitive style. When it was investigated in terms of accuracy, it was found that there was a significant difference between groups according to only small numbers. In terms of reaction type, however, two groups did not differ in terms of both small and big numbers. Moreover, it is seen that field-dependent participants spent more time while they solve subtraction operations with big numbers.

The aim of the study is to develop a scale that could assess illness perception and reaction in patients with COPD. The study was conducted in the patients who were admitted in the pulmonary disease departments of a public and a private hospital. The study included 271 COPD patients. The COPD Perception and Reaction Scale consisting of fifty-four items was prepared as Likert type 5 rating scale. In the validity phase of the study, expert judgments were obtained for content validity then explanatory and confirmatory factor analysis were used. The reliability of the scale in terms of internal consistency was tested with the Cronbach Alpha coefficient. According to the results of the exploratory factor analysis, COPD Perception and Reaction Scale consists of 3 sub-dimensions and 23 items. Factors are named as behavioral reaction, emotional reaction and spiritual reaction. According to confirmatory factor analysis, the goodness-of-fit indices obtained (x2 / df = (676,47 / 227) 2.98 and RMSEA = .056, NFI = .80, CFI = .96, NFI = .91 and AGFI = .85) suggests that the recommended model for the scale is acceptable. The Cronbach’s alpha coefficient was found as .74, and for the sub-dimensions Cronbach’s alpha values were calculated as .87 for “emotional reaction”, .76 for “behavioral reaction” and .79 for “spiritual reaction”. The 23-item form of the COPD Illness Perception and Reaction Scale was demonstrated to be a valid and reliable scale for determining the perception and the reaction towards illness in COPD patients in Turkey. Keywords: chronic obstructive pulmonary disease (COPD), illness perception, reaction

The escalating rate of fossil fuel combustion contributes to excessive CO2 emission and the resulting global climate change has drawn considerable attention. Therefore, tremendous efforts have been devoted to mitigate the CO2 accumulation in the atmosphere. Carbon capture and storage (CCS) strategy has been regarded as one of the promising options for controlling CO2 build-up. However, desorption and compression of CO2 need extra energy input. To circumvent this energy issue, carbon capture and utilization (CCU) strategy has been proposed whereby CO2 can be captured and in situ activated simultaneously to participate in the subsequent conversion under mild conditions, offering valuable compounds. As an alternative to CCS, the CCU has attracted much concern. Although various absorbents have been developed for the CCU strategy, the direct, in situ chemical conversion of the captured CO2 into valuable chemicals remains in its infancies compared with the gaseous CO2 conversion. This review summarizes the recent progress on CO2 capture and in situ catalytic transformation. The contents are introduced according to the absorbent types, in which different reaction type is involved and the transformation mechanism of the captured CO2 and the role of the absorbent in the conversion are especially elucidated. We hope this review can shed light on the transformation of the captured CO2 and arouse broad concern on the CCU strategy.

The value of a specific substrate class for synthetic applications is greatly enhanced if different types of reactions can be performed selectively upon a judicious choice of reaction conditions. In the present study it was shown that the typical photochemical behaviour of naphthaldehydes is completely altered in the presence of Lewis acids. Without Lewis acids, reactions at the carbonyl group are exclusively observed while Lewis acids facilitate a visible light-mediated cycloaddition at the arene core providing access to products of aromatic C–H functionalization via cyclobutane intermediates.

We study a variant of the Cucker-Smale system with reaction-type delay. Using novel backward-forward and stability estimates on appropriate quantities we derive sufficient conditions for asymptotic flocking of the solutions. These conditions, although not explicit, relate the velocity fluctuation of the initial datum and the length of the delay. If satisfied, they guarantee monotone decay (i.e., non-oscillatory regime) of the velocity fluctuations towards zero for large times. For the simplified setting with only two agents and constant communication rate the Cucker-Smale system reduces to the delay negative feedback equation. We demonstrate that in this case our method provides the sharp condition for the size of the delay such that the solution be non-oscillatory. Moreover, we comment on the mathematical issues appearing in the formal macroscopic description of the reaction-type delay system., 19 pages

Slag is an industry by-product of steel-making factories that is widely found in the concrete industry. This study shows a framework for evaluating the hydration heat, reaction amount, and strength progress of cement–slag binary composites. First, a test is conducted to measure the isothermal hydration heat of slag composite paste at various temperatures. Based on the experimental results with cumulative hydration heat, the coefficients of the kinetic reaction type of slag were determined. In addition, the reaction quantity of slag was calculated utilizing a slag reaction model. It is found that the reaction amount of slag is significantly improved at elevated temperatures. The reaction quantity of slag decreases with an increasing content of slag. Second, using the reaction quantity of slag and cement, a straight-line equation is created for evaluating the strength progress of binary composites. The strength progress model applies to a number of slag substitution ratios and curing temperatures. The hydration-based strength model shows better analysis results than maturity-based models.

This review will survey recent developments in the area of the catalytic asymmetric Nozaki–Hiyama–Kishi reaction. The content will be classified according to reaction type as follows: asymmetric allylation, asymmetric propargylation, asymmetric alkynylation, asymmetric vinylation, and asymmetric alkylation. 1 Introduction 2 Asymmetric Allylation 3 Asymmetric Propargylation and Asymmetric Homoallenylation 4 Asymmetric Alkynylation 5 Asymmetric Vinylation and Arylation 6 Asymmetric Alkylation 7 Intramolecular Nozaki–Hiyama–Kishi Reaction 8 Conclusion and Perspectives

Catalytic promiscuity is a useful, but accidental, enzyme property, so finding catalytically promiscuous enzymes in nature is inefficient. Some ancestral enzymes were branch points in the evolution of new enzymes and are hypothesized to have been promiscuous. To test the hypothesis that ancestral enzymes were more promiscuous than their modern descendants, we reconstructed ancestral enzymes at four branch points in the divergence hydroxynitrile lyases (HNL's) from esterases ∼ 100 million years ago. Both enzyme types are α/β-hydrolase-fold enzymes and have the same catalytic triad, but differ in reaction type and mechanism. Esterases catalyze hydrolysis via an acyl enzyme intermediate, while lyases catalyze an elimination without an intermediate. Screening ancestral enzymes and their modern descendants with six esterase substrates and six lyase substrates found higher catalytic promiscuity among the ancestral enzymes (P0.01). Ancestral esterases were more likely to catalyze a lyase reaction than modern esterases, and the ancestral HNL was more likely to catalyze ester hydrolysis than modern HNL's. One ancestral enzyme (HNL1) along the path from esterase to hydroxynitrile lyases was especially promiscuous and catalyzed both hydrolysis and lyase reactions with many substrates. A broader screen tested mechanistically related reactions that were not selected for by evolution: decarboxylation, Michael addition, γ-lactam hydrolysis and 1,5-diketone hydrolysis. The ancestral enzymes were more promiscuous than their modern descendants (P = 0.04). Thus, these reconstructed ancestral enzymes are catalytically promiscuous, but HNL1 is especially so.

Small poly-functionalized heterocycles are frequently found in pharmacophores and play important roles in drug discovery. Heterocyclic ketene aminals (HKAs) are versatile building blocks for the synthesis of a variety of heterocyclic compounds. In recent years, there has been significant progress in the chemistry of HKAs. All previous work focused on the developments of HKAs in reaction type. This review focused on the developments of HKA-based synthesis of various heterocyclic nuclei since 2002. We believe this will give some insights and help to bring about new ideas for further research.

This chapter reviews the literature through the end of 2016 directed to the preparation and use of heterocyclic chiral auxiliaries derived for terpenes, principally camphor, borneol (via ent-camphor), and pinene. Since they are closely aligned in their utility, the scope of this chapter was expanded somewhat to include non-heterocyclic chiral auxiliaries derived from these terpenes where relevant and appropriate. The chapter is organized by auxiliary, and within the section on a given auxiliary are subsections on preparation and the various applications of that auxiliary to asymmetric synthesis organized generally by reaction type. A wide variety of applications are reviewed including cycloadditions, condensations, sigmatropic rearrangements, alkylations, and acylations to name a few. While the chapter is not intended to be comprehensive, it is intended to give the reader the scope and breadth of the structural types of auxiliaries derived from camphor, borneol, and pinene and their applications to asymmetric synthesis.