Condensation Step Research Articles

Tandem Electrochemical Redox/Condensation Reaction Between 2‐Amino Nitrobenzenes and Aliphatic Alcohols: An Approach to Benzimidazoles

AbstractTandem reactions via electrocatalytic annulations have emerged as a strategy for the construction of heterocycles. Herein, a two‐component electrochemical annulation via sequential reduction, oxidation, and condensation steps to synthesize valuable benzimidazoles motifs is reported. This reaction, which utilizes electricity as both the oxidants and reductants, tolerates a broad range of functional groups. Detailed mechanistic studies including control experiments, cyclic voltammetry (CV) analysis, and key reaction intermediate characterization, reveals an intermolecular electrochemical redox/cyclization pathway.

Biomimetic and Concise Total Syntheses of Prenylated and Bicyclo[2.2.2]diazaoctane-Containing Indole Alkaloids Including Taichunamide A, Notoamide N and Versicolamide B.

Total syntheses of the title prenylated indole alkaloids together with seven others are reported. Biogenetic considerations have been employed in devising the reaction sequences leading to these targets with, in the opening stages, electrochemically-derived indole-3-carboxaldehyde 15 being subject to an aldol-type condensation reaction involving diketopiperazine derivative 19. This led, after prototopic shifts, intramolecular Diels-Alder cycloaddition and hydrolysis/deprotection steps, to the racemic forms of the bicyclo[2.2.2]diazaoctane-containing natural product stephacidin A (2) and its C6 epimer 3. Epoxidation of the last compound afforded, following rearrangement of the primary oxidation products, a mixture of (±)-taichunamide A [(±)-4] and (±)-versicolamide B [(±)-7]. Related protocols allowed for the conversion of (±)-stephacidin A [(±)-2] into (±)-notoamide B [(±)-5]. Analogous aldol condensation, nucleophilic reduction, and epoxidation steps led to the formation of (-)-notoamide E and its conversion into notoamide C as well as the indole fragmentation product amoenamide E. A late-stage chlorination reaction applied to (±)-stephacidin A provided access to the spirocyclic oxindole (±)-notoamide N [(±)-6].

A novel Ni-complex nanocatalyst for efficient electrochemical oxidation of alcohol in alkaline medium: Mechanism and DFT study

A novel catalyst based on nanoparticles of Ni(II) complex was developed to enhance the activity toward alcohol oxidation and hence its possible application in direct alcohol fuel cells (DAFCs). The [NiII(ABP)2] complex was formed in a molar ratio 1(Ni):2(ABP), where (ABP) was synthesized based on 4-(Dimethylamino)benzaldehyde (DMBA), 4-Aminoantipyrine (AAP) and 2-aminophenol (AP) through two condensation steps. Several characterization techniques were used to evaluate the structure of the synthesized compounds, such as elemental analysis, mass, FTIR, UV–Vis, 1HNMR , magnetic, molar conductance and XRD. Transmission and scanning electron microscope (TEM and SEM) images of separated [NiII(ABP)2] complex revealed particles with a size lower than 26 nm. SEM for [NiII(ABP)2]/GCE before and after ethanol oxidation was performed along with EDX and mapping techniques. The computational DFT (density functional theory) calculations supported the octahedral geometry shape of the prepared [NiII(ABP)2] chelate. Several octahedral structures involved in a purposed mechanism were studied using DFT to show the expected optimized shapes formed during ethanol oxidation. Also, the alcohol adsorption simulation was performed using Dmol3 numerical DFT modules to calculate the adsorption energy of alcohols on nickel complex surface. Additionally, the activity toward oxidation of alcohols with different sizes and stereochemistry (methanol, ethanol, propanol, and isopropanol) was investigated in an alkaline medium. The electrode activity was represented for each alcohol as a function of anodic oxidation current. Whereas the electrode achieved 14, 26, 6, and 4 mA cm−2 for methanol, ethanol, propanol, and isopropanol, respectively. Moreover, several parameters were calculated to judge the electrode performance, like diffusion coefficient, catalytic rate constant, stability, Tafel slope, and charge transfer resistance. The theoretical calculations and the experimental findings strongly correlate with each other, where Ni-complex showed the greatest catalytic activity toward ethanol oxidation.

The structure of the Orm2-containing serine palmitoyltransferase complex reveals distinct inhibitory potentials of yeast Orm proteins

Sphingolipid levels are crucial determinants of neurodegenerative disorders and therefore require tight regulation. The Orm protein family and ceramides inhibit the rate-limiting step of sphingolipid biosynthesis-the condensation of L-serine and palmitoyl-coenzyme A (CoA). The yeast isoforms Orm1 and Orm2 form a complex with the serine palmitoyltransferase (SPT). While Orm1 and Orm2 have highly similar sequences, they are differentially regulated, though the mechanistic details remain elusive. Here, we determine the cryoelectron microscopy structure of the SPT complex containing Orm2. Complementary invitro activity assays and genetic experiments with targeted lipidomics demonstrate a lower activity of the SPT-Orm2 complex than the SPT-Orm1 complex. Our results suggest a higher inhibitory potential of Orm2, despite the similar structures of the Orm1- and Orm2-containing complexes. The high conservation of SPT from yeast to man implies different regulatory capacities for the three human ORMDL isoforms, which might be key for understanding their role in sphingolipid-mediated neurodegenerative disorders.

Pyrene based AIE-active probe for selective detection of picric acid through the inner filter effect channel in aqueous medium

The development of pyrene derivatives possessing the AIE feature have emerged as an intriguing area of research with potential applications in several domains. In the present study, we designed and developed an AIE active pyrene derivative for picric acid sensing in an aqueous medium. The design based on a single step condensation reaction and the product has been meticulously characterized by using NMR and Mass spectrometric techniques. In comparison to pristine pyrene, the synthesized pyrene derivative has a lower bandgap energy as a result of the intramolecular charge transfer between pyrene and 4-(methylthio)-2-oxo-2H-pyran-3-carbonitrile. The synthesized probe demonstrates a moderate level of fluorescence when dissolved in a solution, and it has exhibited a remarkable emission caused by aggregation at higher water percentages. The aggregates were meticulously characterized by DLS, SEM and TEM measurements. The spherically shaped aggregates have shown enhanced fluorescence quantum yield and lifetime, rendering them a more suitable option for sensor applications. The aggregates were effectively employed as a fluorescent probe for the detection of picric acid in an aqueous medium. The probe exhibited a notable level of selectivity and sensitivity towards picric acid, as evidenced by its low detection limit of 4.47 nM. Moreover, the quenching mechanism was ascribed to the inner filter effect, providing supporting evidence from both experimental and mathematical calculations. The findings indicate that the probe has potential as a feasible choice for a picric acid sensor.

Stress-induced nucleoid remodeling in Deinococcus radiodurans is associated with major changes in Heat Unstable (HU) protein dynamics.

Bacteria have developed a wide range of strategies to respond to stress, one of which is the rapid large-scale reorganization of their nucleoid. Nucleoid associated proteins (NAPs) are believed to be major actors in nucleoid remodeling, but the details of this process remain poorly understood. Here, using the radiation resistant bacterium D. radiodurans as a model, and advanced fluorescence microscopy, we examined the changes in nucleoid morphology and volume induced by either entry into stationary phase or exposure to UV-C light, and characterized the associated changes in mobility of the major NAP in D. radiodurans, the heat-unstable (HU) protein. While both types of stress induced nucleoid compaction, HU diffusion was reduced in stationary phase cells, but was instead increased following exposure to UV-C, suggesting distinct underlying mechanisms. Furthermore, we show that UV-C-induced nucleoid remodeling involves a rapid nucleoid condensation step associated with increased HU diffusion, followed by a slower decompaction phase to restore normal nucleoid morphology and HU dynamics, before cell division can resume. These findings shed light on the diversity of nucleoid remodeling processes in bacteria and underline the key role of HU in regulating this process through changes in its mode of assembly on DNA.

Revisiting decade-old questions in proanthocyanidin biosynthesis: current understanding and new challenges.

Proanthocyanidins (PAs), one of the most abundant natural polymers found in plants, are gaining increasing attention because of their beneficial effects for agriculture and human health. The study of PA biosynthesis has been active for decades, and progress has been drastically accelerated since the discovery of key enzymes such as Anthocyanidin Reductase (ANR), Leucoanthocyanidin Reductase (LAR), and key transcription factors such as Transparent Testa 2 (TT2) and Transparent Testa 8 (TT8) in the early 2000s. Scientists raised some compelling questions regarding PA biosynthesis about two decades ago in the hope that addressing these questions would lead to an enhanced understanding of PA biosynthesis in plants. These questions focus on the nature of starter and extension units for PA biosynthesis, the stereochemistry of PA monomers and intermediates, and how and where the polymerization or condensation steps work subcellularly. Here, I revisit these long-standing questions and provide an update on progress made toward answering them. Because of advanced technologies in genomics, bioinformatics and metabolomics, we now have a much-improved understanding of functionalities of key enzymes and identities of key intermediates in the PA biosynthesis and polymerization pathway. Still, several questions, particularly the ones related to intracellular PA transportation and deposition, as well as enzyme subcellular localization, largely remain to be explored. Our increasing understanding of PA biosynthesis in various plant species has led to a new set of compelling open questions, suggesting future research directions to gain a more comprehensive understanding of PA biosynthesis.

Multicomponent Synthesis of α-Branched Amines via a Zinc-Mediated Carbonyl Alkylative Amination Reaction.

Methods for the synthesis of α-branched alkylamines are important due to their ubiquity in biologically active molecules. Despite the development of many methods for amine preparation, C(sp3)-rich nitrogen-containing compounds continue to pose challenges for synthesis. While carbonyl reductive amination (CRA) between ketones and alkylamines is the cornerstone method for α-branched alkylamine synthesis, it is sometimes limited by the sterically demanding condensation step between dialkyl ketones and amines and the more restricted availability of ketones compared to aldehydes. We recently reported a "higher-order" variant of this transformation, carbonyl alkylative amination (CAA), which utilized a halogen atom transfer (XAT)-mediated radical mechanism, enabling the streamlined synthesis of complex α-branched alkylamines. Despite the efficacy of this visible-light-driven approach, it displayed scalability issues, and competitive reductive amination was a problem for certain substrate classes, limiting applicability. Here, we report a change in the reaction regime that expands the CAA platform through the realization of an extremely broad zinc-mediated CAA reaction. This new strategy enabled elimination of competitive CRA, simplified purification, and improved reaction scope. Furthermore, this new reaction harnessed carboxylic acid derivatives as alkyl donors and facilitated the synthesis of α-trialkyl tertiary amines, which cannot be accessed via CRA. This Zn-mediated CAA reaction can be carried out at a variety of scales, from a 10 μmol setup in microtiter plates enabling high-throughput experimentation, to the gram-scale synthesis of medicinally-relevant compounds. We believe that this transformation enables robust, efficient, and economical access to α-branched alkylamines and provides a viable alternative to the current benchmark methods.

Reflection in Pixels: Scrutinizing Students' Perspectives on Digital Reflective Journals

Reflection plays an important role in language learning. Through reflection, students are encouraged to learn how to learn to acquire deeper learning. This study investigates students’ perceptions of digital reflective journals as a means of reflective practice in their ESP classroom. This study involved 45 students who enrolled in a Business English class where they were required to write reflective journals digitally at the end of the teaching and learning process. This study used questionnaires and semi-structured interviews as the instruments to collect the data. The quantitative data from the questionnaire were analysed with the assistance of SPSS to examine the frequency of students’ responses to each statement listed on the questionnaire. Meanwhile, the qualitative data from semi-structured interviews were analysed through the steps of data condensation, data display, and conclusion. The findings of this study revealed that students admitted to the beneficial roles of digital reflective journals. It helped them raise their self-awareness, and develop their critical and problem-solving skills. Besides, they also assumed that writing reflective journals digitally was more convenient because it offered ease of access and flexibility. Therefore, digital reflective journals can serve as valuable tools to improve the quality of language learning that can be considered to be utilized in language classrooms.

Implementation of the Calistung Program in Phase A at the Sekolah Penggerak Program and the Sekolah Pengimbas Program

<em>This research was conducted at SDN Balerejo 02 Madiun as a Driving School and SDN Garon 02 Madiun as a Driving School. The research approach applied is qualitative research with a case study design. The data collection techniques used were observation, interviews and documentation. Data analysis was carried out by applying a descriptive qualitative interactive model approach through the steps of data collection, data condensation, data display, and conclusion: drawing/verifying. The research results show that the implementation of the Calistung program in phase A at Driving Schools and Imposing Schools is carried out by providing additional hours after teaching and learning activities on certain days. The implementation of the Calistung program uses contextual/real learning methods accompanied by several reading books, letter cards and number cards. The teacher also provides books that students are interested in as reading sources, introducing numbers using basic arithmetic operations. The obstacles to implementing the Calistung are difficulties in providing learning media, the use of inappropriate methods, and various types of assessments. Another obstacle is the lack of availability of suitable books.</em>

The Effectiveness of academic Self-Efficacy and Learning Pancasila Values to Reduce Bullying Behavior in Elementary School Students

<p><em>Bullying behavior is a serious problem in schools. Bullying behavior can be carried out physically or non-physically, either through social media or directly, so that students feel threatened, afraid, traumatized, and it has a big impact on learning activities. This research focuses on the effectiveness of academic self-efficacy and learning Pancasila values to reduce bullying behavior in students. This research uses a qualitative approach with a case study type of research. The data used are the results of observations, interviews, questionnaires and documentation. To obtain valid data, this research applies source triangulation and method triangulation. The analysis was carried out by applying a descriptive qualitative interactive model approach through the steps of data collection, data condensation, data display, and conclusion: drawing/verifying. The research results show that the application of Pancacila values has a role in shaping character because each value of the Pancasila principles contains behavioral guidelines that must be applied in everyday life. In this case, the application of Pancasila values can reduce bullying behavior from both the perpetrator and the victim. Academic self-efficacy influences how students interpret environmental situations, anticipation, strategies, and actions that can be taken to minimize the impact of bullying behavior.</em></p>

Analysis of Entrepreneurship in The Project for Strenghthening the Profile of Pancasila Students (P5) Activities

<p><em>This research focuses on the analysis of entrepreneurship in the Project for Strengthening the Profile of Pancasila Students (P5) activities in elementary schools. This research uses a qualitative approach with descriptive research type. The data used is the result of observation, interviews and documentation. The analysis was carried out by applying a descriptive qualitative interactive model approach through the steps of data collection, data condensation, data display, and conclusion: drawing/verifying. The research results show that 1) The planning stages carried out in P5 activities in the context of entrepreneurship are a) choosing a theme; b) elect a coordinator; c) form a team; d) determine the supervisory team; e) determine the topic; f) determine the implementation time; and 7) developing modules; 2) With the theme of entrepreneurship, P5 can improve the entrepreneurial spirit because students are taught to make products that have selling value. Through entrepreneurial activities, students become embedded with an independent, creative, innovative, big-hearted spirit, and can explore the potential around them; and 3) Evaluation of P5 activities in the context of entrepreneurship paying attention to input and process aspects that focus on strategic planning, scheduling, process assessment, budgeting and active participation of school residents, especially teachers and students</em></p>

Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods.

CeO2 nanorod based catalysts for the base-free synthesis of azoxy-aromatics via transfer hydrogenation of nitroarenes with ethanol as hydrogen donor have been synthesized and investigated. The oxygen vacancies (Ov ) and base sites are critical for their excellent catalytic properties. The Ov , i.e., undercoordinated Ce cations, serve as the sites to activate ethanol and nitroarenes by lowering the energy barrier to transfer hydrogen from α-Csp3 -H in ethanol to the nitro group coupling it to the redox reactions between Ce3+ and Ce4+ . At the same time, the base sites catalyze the condensation step to selectively produce azoxy-aromatics. The catalytic route opens a much improved way to use non-noble metal oxides without additives for the selective functional group reduction and coupling reactions.

Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods

AbstractCeO2 nanorod based catalysts for the base‐free synthesis of azoxy‐aromatics via transfer hydrogenation of nitroarenes with ethanol as hydrogen donor have been synthesized and investigated. The oxygen vacancies (Ov) and base sites are critical for their excellent catalytic properties. The Ov, i.e., undercoordinated Ce cations, serve as the sites to activate ethanol and nitroarenes by lowering the energy barrier to transfer hydrogen from α−Csp3−H in ethanol to the nitro group coupling it to the redox reactions between Ce3+ and Ce4+. At the same time, the base sites catalyze the condensation step to selectively produce azoxy‐aromatics. The catalytic route opens a much improved way to use non‐noble metal oxides without additives for the selective functional group reduction and coupling reactions.

Bioethanol separation by a new pass-through distillation process

Distillation is the most used separation technology at industrial-scale, but using distillation in bio-based processes (e.g. fermentation processes to produce bioethanol) is quite challenging when mild temperatures are needed to keep the microbes alive. Vacuum distillation can be used to perform evaporation at low temperatures, but setting a low distillation pressure fixes also the condensation temperature to very low values that may require expensive refrigeration.Pass-through distillation (PTD) is an emerging hybrid separation technology that effectively combines distillation with absorption in a sorption-assisted distillation process that decouples the evaporation and condensation steps. This is achieved by inserting between the evaporation and condensation steps an absorption-desorption loop that passes through the component to be separated and allows the use of different pressures and types of heating and cooling utilities.This paper is the first to present the process design and rigorous simulation (implemented in Aspen Plus) of a new pass-through distillation process for bioethanol (∼100 ktonne/y plant capacity), proving its effectiveness in concurrent alcohol recovery and fermentation (CARAF). Combining PTD with heat pumps leads to low recovery costs of 0.122 $/kgEtOH and energy requirements of only 1.723 kWthh/kgEtOH. Alternatively, combining PTD with multi-effect distillation resulted in 0.131 $/kgEtOH recovery costs and 1.834 kWthh/kgEtOH energy intensity.

Modified plywood binder preparation process: The effect of urea formaldehyde mole ratio

The paper highlights the importance of reducing formaldehyde emissions in plywood products due to increasing public health awareness. Lowering the formaldehyde to urea mole ratio (F/U) during UF resin preparation is a crucial step in achieving this goal. The study focuses on synthesizing UF resin through alkaline-acid process modification involving a strong acid step at the initial stage with a target viscosity range of 120 140 cP. Different F/U ratios were investigated at various condensation steps, with final molar ratios ranging from 1.5 to 1.0. Results indicate that adjusting the F/U ratio during the fourth condensation step (F/U4) is essential to meet desired viscosity requirements. Lower F/U4 ratios lead to decreased reactivity and reduced free formaldehyde content. Resin aging resulted in increased viscosity and gel time, but all resins remained suitable for application for up to three weeks after preparation. Application tests revealed that UF resin with lower F/U4 ratios produced plywood with reduced internal bonding (IB) strength and formaldehyde emissions. F/U4 = 1.1 was found to be the lowest acceptable molar ratio, with formaldehyde emissions of approximately 2 mg/L. These findings stress the importance of optimizing the UF resin synthesis process to achieve lower formaldehyde emission plywood products.

Penerapan Model Pembelajaran Improve Pada Materi Nahwu Dalam Meningkatkan Maharoh Qiro’ah Santri PP Darul Lughah Wal Karomah

Learning in class is often considered a boring and boring experience by students or students. The learning model that is generally used by teachers is the classical and monotonous model, and this often results in difficulties for students in understanding the material presented. This study aims to explain the application of the "Improve" learning model to Nahwu material and evaluate its impact on increasing the qiro'ah spirit in PP Darul Lughah Wal Karomah. This research uses qualitative methods with a case study approach focused on PP Darul Lughah Wal Karomah in Sidomukti Kraksaan Probolinggo and involves the participation of 20 students as respondents. Data collection methods used include observation, interviews, and documentation. The data analysis process we apply is descriptive analysis, which involves the steps of data collection, data condensation, and drawing conclusions. The interim results of this study show that the application of the "Improve" learning model in learning Nahwu Science has had a positive impact. The learning atmosphere in the classroom has changed to be more enthusiastic, and the students find it easier to apply Nahwu's rules in the practice of reading the turast. This research tries to overcome the problem of boring and monotonous learning and offers an effective alternative in increasing the understanding and motivation of learning students in the pesantren environment.

Computational Studies towards the Optimization of the Synthesis of 1,2,4‐Triazolo[1,5‐a]pyridine‐2‐carboxylate: Advantages of Continuous Flow Processing

AbstractSeveral strategies to synthesize desired 1,2,4‐triazolo[1,5‐a]pyridine‐2‐carboxylate targets have been reported over the years. The most convenient way features the preparation of the precursor triazolopyridine‐N‐oxide through a condensation step between sulfilimines and a nitrile oxide species, followed by a deoxygenation step. This paper presents a detailed work on the synthesis of [1,2,4]triazolo[1,5‐a]pyridine‐2‐carboxylate‐N‐oxide, featuring a synergistic experimental‐theoretical approach. Herein, we report the development of an efficient and straightforward method to prepare ethyl [1,2,4]triazolo[1,5‐a]pyridine‐2‐carboxylate 3‐oxide in continuous flow. The transfer from batch to flow processing resulted in a significant boost in isolated yield (53 % vs. 31 %) and a decrease in the simultaneous presence of starting materials and product in the reaction media from 4 hours to 3.5 minutes. An in‐depth mechanistic study of the reaction using density functional theory provided a deeper understanding of the whole reaction manifold and key indications on how to further improve the process in flow.

Peningkatan Minat Siswa dalam Meneliti Sejarah Lokal melalui Program Kunjungan Museum Perjuangan Rakyat Jambi

This study aims to determine the effect of the Museum Perjuangan Rakyat Jambi on interest in researching local history for MAN Insan Cendekia Jambi students. This research is useful to be a reference material for related parties in optimizing the role and function of museums and increasing interest in research among students, especially in history subjects. This research is a quantitative research with a qualitative approach. Data was collected using observation, interview and questionnaire steps. The data analysis technique used in this research is percentage analysis with the formula P = f / N x 100%. Furthermore, the data were analyzed using the Miles and Huberman model with the steps of Data Condensation, Data Display and Conclusion drawing / verification. The research sample was taken using the Slovin technique with a population of 115 people and a sample of 35 people. The results showed that the Jambi People's Struggle Museum had an effect of 83.42% on the interest in researching the local history of Jambi MAN Insan Cendekia students. Of the 15 statement items given to respondents, 10 statement items received very good qualifications, 4 statement items were classified as good qualifications and only 1 statement item was included in the deficient category. So it can be concluded that the Jambi People's Struggle Museum has a very good effect on the interest in researching local history of Jambi MAN Insan Cendekia students.

Synthesis of β-(4-chlorophenyl) lactic acid

β-(4-chlorophenyl)lactic acid was synthetized via four steps of reaction, knoevenagel condensation, oxazolone ring-opening, hydrolysis and clemmensen reduction, staring from commercially available compound 4-chlorobenzaldehyde. β-(4-chlorophenyl) lactic acid and its mid-products were identified with 1H NMR, 13C NMR and MS. The spectra and physical constants were concordant with the corresponding structures and properties. The synthetic route we used has the advantages of abundant materials, simple process, mild reaction, without special equipments, much lower costs, ect.