Reaction Sequence Research Articles

The 3D plan analysis under progressive collapse for RC buildings through demand capacity ratio (DC) for three levels of damage

The progressive collapse presents a sudden load may cause initial failure in local parts at the frame which could lead to sequence reactions in the elements of the structure. A building of seven storeys was chosen to designed under gravity load according ACI 318 Code. This building is analyzed under progressive collapse condition for two columns damage cases; edge damage, corner damage. The building needs to be loaded as specified according (GSA) General Services Administration requirements through linear static analysis. The results of linear analysis show the variation in ((DC)) demand capacity ratio for the columns. The aspects of damage action in this study regarding section size and damage cases with 100% damage column loss (full damage), 60% damage (0.6 section size), 80% damage (0.8 section size). A GSA guideline to typical building with (DC) values bigger than 1.5 refer to critical potential damage conditions at the columns of the frame. It can be seen of the results the effect of size reduction for the building. This effect is clear to be decreased along distance from any plan. The((DC)) for columns which exceeded 1.5 value which show risky damage condition could actually happened that present serious threat possibility specially for nominated columns C22, C29 and C23 at plans A and B which show middle columns at lower position of the building.

Step-by-step synthetic route to access eugenol-1,2,3-triazole-chalcone hybrid

Molecular hybridization represents a strategic approach in drug design, where two or more pharmacophoric elements from distinct bioactive molecules are integrated into a single hybrid compound. In this study, we synthesized hybrid compounds of chalcone, triazole, and eugenol through straightforward reactions using 4-hydroxyacetophenone as the starting material. Initially, 4-hydroxyacetophenone (1) underwent alkylation with 1,4-dibromobutane to produce compound 2 with an 84 % yield. Compound 2 was then subjected to azidation, resulting in azidobutoxyacetophenone 3 with a 71 % yield. Subsequently, compound 3 was reacted with either benzaldehyde or 4-methoxybenzaldehyde via base-catalyzed aldol condensation, yielding azidobutoxychalcones 4a (69 %) and 4b (84 %). Finally, azide-alkyne [3+2] cycloaddition between 4a/4b and propargylated eugenol afforded chalcone derivatives bearing eugenol-1,2,3-triazole hybrids 5a and 5b, each with a 90 % yield.•Synthesized chalcones featuring an eugenol-1,2,3-triazole scaffold using 4-hydroxyacetophenone as the starting material.•Synthesis was accomplished through a four-step reaction sequence.•Products were obtained in good yield.

α,β-Dehydrogenation Adjacent to Sulfur- and Phosphorus- Containing Compounds.

Here, we report a robust nickel-catalyzed α,β-dehydrogenation process designed for substrates that contain electron-withdrawing sulfur and phosphorus groups. Leveraging the formation of organozinc intermediates and the utilization of a mild oxidant, allyl methyl carbonate, this methodology exhibits remarkable efficiency and outstanding diastereoselectivities across a diverse array of substrates, achieving E:Z ratios exceeding 20:1. Investigation through deuterium incorporation studies and an analysis of the reaction sequence leading to the formation of the dehydrogenative allylation side product, provide useful insights into reaction optimization.

Tantalum Catalyzed Hydroaminoalkylation Enables a Telescoping Catalytic Reaction Sequence for the Synthesis of Benzoannulated Indolizidines and Quinolizidines

Tantalum Catalyzed Hydroaminoalkylation Enables a Telescoping Catalytic Reaction Sequence for the Synthesis of Benzoannulated Indolizidines and Quinolizidines

A new exploration of the amplification mechanism of saltatory rolling circle amplification (SRCA) for food safety detection

A new property of Bst DNA polymerase was discovered by our team, which led to the establishment of a new isothermal amplification method for SRCA nucleic acid, which was applied to food safety detection, investigated the amplification mechanism, and the SRCA version 1.0 amplification mechanism was proposed. This study proposes a new SRCA amplification mechanism (version 2.0) by using the autosynthetic sequences CDG2040 and CDG2068, as well as the Listeria monocytogenes hlyA gene and Vibrio parahaemolyticus toxR gene as target sequences to further investigate the amplification mechanism. The initiation of the SRCA reaction depends primarily on the spatial structure of the non-closed circle formed by the discontinuous complementation of the bases on both sides of the target sequence. The DNA fragments that connect the target sequences in the SRCA reaction are the sum of the complementary sequences of adjacent partial sequences on both sides of the target sequence.

Linkage of alternative exon assembly in Drosophila TrpA1 transcripts

Drosophila TrpA1 (transient receptor potential ankyrin 1) transcripts are alternatively spliced at two distinct sites each with a choice of mutually exclusive exons. The first site determines exon1 encoding the amino terminus to produce either nucleophile-, electrophile- and noxious temperature-gated TRPA1(A) or electrophile- and innocuous warmth-gated TRPA1(B). The second site selects for exon10, resulting in TrpA1 variants with either exon10a or exon10b encoding a domain between the N-terminal ankyrin repeats and the transmembrane segments. Although unbiased assembly would generate TRPA1 with four different domain combinations, the functional impact of these alternative domains remains to be thoroughly examined. Here, we find that there is a relatively strong linkage in mRNA splicing between the two sites in case of TrpA1(B), but not TrpA1(A), transcripts. Our semi-quantitative assay, consisting of reverse transcription polymerase chain reaction (RT-PCR) and Sanger sequencing, revealed that exon10b is little coupled with TrpA1(B) transcripts, suggesting that only three isoforms, TRPA1(A)-exon10a [denoted as TRPA1(A)], TRPA1(A)-exon10b [TRPA1(A)10b] and TRPA1(B)-exon10a [TRPA1(B)], are present at detectable levels using our method. Interestingly, heterologously expressed TRPA1(A)10b showed elevated sensitivity to low concentrations of N-methyl maleimide (NMM), a cysteine-modifying electrophile, compared with other isoforms. Equivalent isoforms in malaria-transmitting Anopheles gambiae displayed a similar pattern of isoform-dependent NMM dose dependences, suggesting that the chemosensory regulation by selective domain assembly is conserved in insect TRPA1s. Thus, alternative RNA splicing of exon10 is coordinated in conjunction with the first exons, regulating chemical sensitivity of insect TRPA1s.

Impact of next-generation sequencing vs polymerase chain reaction testing on payer costs and clinical outcomes throughout the treatment journeys of patients with metastatic non-small cell lung cancer.

For patients with metastatic non-small cell lung cancer (mNSCLC), next-generation sequencing (NGS) biomarker testing has been associated with a faster time to appropriate targeted therapy and more comprehensive testing relative to polymerase chain reaction (PCR) testing. However, the impact on payer costs and clinical outcomes during patients' treatment journeys has not been fully characterized. To assess the costs and clinical outcomes of NGS vs PCR biomarker testing among patients with newly diagnosed de novo mNSCLC from a US payers' perspective. A Markov model assessed costs and clinical outcomes of NGS vs PCR testing from the start of testing up to 3 years after. Patients entered the model after receiving biomarker test results and then initiated first-line (1L) targeted or nontargeted therapy (immunotherapy and/or chemotherapy) depending on actionable mutation detection. A few patients with an actionable mutation were not detected by PCR and inappropriately initiated 1L nontargeted therapy. At each 1-month cycle, patients could remain on treatment with 1L, progress to second line or later (2L+), or die. Literature-based inputs included the rates of progression-free survival (PFS) and overall survival (OS), targeted and nontargeted therapy costs, total costs of testing, and medical costs of 1L, 2L+, and death. Per patient average PFS and OS as well as cumulative costs were reported for NGS and PCR testing. In a modeled population of 100 patients (75% commercial and 25% Medicare), 45.9% of NGS and 40.0% of PCR patients tested positive for an actionable mutation. Relative to PCR, NGS was associated with $7,386 in savings per patient (NGS = $326,154; PCR = $333,540) at 1 year, driven by lower costs of testing, including estimated costs of delayed care and nontargeted therapy initiation before receiving test results (NGS = $8,866; PCR = $16,373). Treatment costs were similar (NGS = $305,644; PCR = $305,283). In the PCR cohort, the per patient costs of inappropriate 1L nontargeted therapy owing to undetected mutations were $6,455, $6,566, and $6,569 over the first 1, 2, and 3 years, respectively. Relative to PCR testing, NGS was associated with $4,060 in savings at 2 years and $1,092 at 3 years. Patients who initiated 1L targeted therapy had an additional 5.4, 8.8, and 10.4 months of PFS and an additional 1.4, 3.6, and 5.3 months of OS over the first 1, 2, and 3 years, respectively, relative to those who inappropriately initiated 1L nontargeted therapy. In this Markov model, as early as year 1, and over 3 years following biomarker testing, patients with newly diagnosed de novo mNSCLC undergoing NGS testing are projected to have cost savings and longer PFS and OS relative to those tested with PCR.

Tracking the coupling conversion of C1-C4 aldehydes with methanol-to-hydrocarbon reaction

Small-molecule aldehydes are promising additives to regulate product distribution in methanol-to-hydrocarbon (MTH) reaction. Herein, the co-feeding of C1-C4 aldehydes with methanol resulted in a significant increase in aromatic formation with the order: acetaldehyde > formaldehyde > propanal ≈ butanal. The mechanistic basis for this enhancement in aromatic production derived from both a direct participation pathway of aldehydes and an indirect pathway via driving the aromatic-based cycle. C2+ aldehydes could undergo multiple aldol-condensation on Brønsted acid sites to form larger alkenals, followed by sequential cyclization-dehydration reaction to cycloalkenes or aromatic species. The Prins reaction could be extended to all C1-C4 aldehydes with alkenes by generating the corresponding dienes. The hydrogen transfer from methanol to C2+ aldehydes produced C2+ olefins and formaldehyde, which would lead to extra formaldehyde-mediated aromatic formation pathway. The intricate evolution pathway of C1-C4 aldehydes in MTH reaction was constructed by detecting abundant oxygenate and hydrocarbon intermediates.

The stage- and kinetics-dependent regulation of highly ordered sequential reactions by liquid–liquid phase separation

Understanding the reaction kinetics, thermodynamics, and molecular mechanisms of liquid–liquid phase separation (LLPS) holds immense significance in unraveling the cell’s spatiotemporal coordination of metabolic pathways and has the potential to revolutionize diverse fields, including diagnostics and catalysis. However, the current scope of LLPS-based investigations is primarily limited to simplistic models with one or two-step reactions, failing to capture the complexity necessary for comprehending LLPS’s impact on intricate reactions and hindering its widespread practical applications. In this study, we address this limitation by constructing and screening a tailored LLPS system and utilizing complex nucleic acid amplification as a representative example. Our findings reveal a significant departure from the continuous acceleration observed in simple reactions, as the acceleration of complex reactions is highly dependent on the kinetics and reactant concentration of each specific reaction stage. Furthermore, by incorporating LLPS and its stage-specific factors, we demonstrate the development of an LLPS-based molecular diagnostic tool with a shortened detection time, higher efficiency and sensitivity compared to traditional methods. Therefore, this newfound understanding sheds light on the intricate characteristics of LLPS-mediated complex reactions and offers a breakthrough in diagnostic advancements by enabling faster and more accurate detection of target molecules, leveraging LLPS in diagnostic advancements, and driving the unlocking of further potential for LLPS utilization in various fields.

Nitrogen-doped mesoporous carbon as metal-free catalysts for the aerobic oxidation of alcohols

The selective oxidation of alcohols to carbonyl compounds is a crucial reaction in organic chemistry. In this study, we report the synthesis of nitrogen-doped mesoporous carbon material by hard template method using biomass derivative sucrose and melamine as carbon and nitrogen sources and silica sol as template agent. Using molecular oxygen as the oxidant, the obtained NC-900 exhibits excellent selectivity in the oxidation of primary alcohols to the corresponding aldehydes without generating over-oxidized acid. For example, under optimal reaction conditions, 4-methoxybenzyl alcohol is almost quantitatively converted to 4-methoxybenzaldehyde. The catalytic system showed robust tolerance to sensitive functional groups and demonstrated favorable reaction effects in gram-scale experiments and multi-step, one-pot reaction sequences. The catalyst was reused for 5 times, and its catalytic activity did not decrease significantly. Hammett correlation studies indicated that the reaction favored substrates with electron-donating substituents. Characterization and experimental results indicate that the synergistic effect of graphitic N and mesoporous structure plays a pivotal role in enhancing the catalytic activity of NC-900 in this transformation. The mechanism study shows that the reaction involves free radical process.

Aromatic (co)polycarbonates bearing pendant 2,3-dimethylmaleimido group based upon a new phthalimidine-containing “cardo” bisphenol

A new “cardo” bisphenol viz., 1-(2-(1,1-bis(4-hydroxyphenyl)-3-oxoisoindolin-2-yl)ethyl)-3,4-dimethyl-1H-pyrrole-2,5-dione (PPH-MA) was synthesized in a two-step reaction sequence starting from phenolphthalein. PPH-MA was utilized as a step-growth monomer for the synthesis of a homo- and fourco-polycarbonates bearing pendant 2,3-dimethylmaleimido groups (PC-MAs) via solution polycondensation of PPH-MA or various mol % compositions of PPH-MA and bisphenol-A, respectively, with triphosgene.1H NMR spectroscopy confirmed the chemical structure and composition of PC-MAs. Inherent viscosity and number average molecular weight values of PC-MAs were in the range 0.45–0.64 dL g−1 and 18,300 − 36,200 g mol−1, respectively, indicating the formation of polymers of medium to reasonably high molecular weights. Tough, transparent and flexible films of PC-MAs could be cast from chloroform solution. X-ray diffraction studies indicated the amorphous nature of PC-MAs. The 10% weight loss temperature (T10) values of PC-MAs were in the range 373–443 °C indicating their good thermal stability.

Molecular genetic monitoring of HIV-1 variants circulating in St. Petersburg

The aim of the study: to assess the genetic diversity of HIV-1 variants circulating in St. Petersburg.Materials and methods. The study included 289 patients with virological ART failure in 2022 in the St. Petersburg AIDS Center. Fragments of the pol gene encoding integrase, reverse transcriptase and protease were analyzed by polymerase chain reaction and Sanger sequencing. Phylogenetic tree created by the Neighbor-joining method with 1000 repeats of nucleotide sequences, bootstrap values >70. To assess the circulation of HIV genovariants in dynamics in St. Petersburg, sequences and clinical and laboratory parameters obtained from 544 patients since 2018. The total sample included 833 samples (289 were collected in 2022), compared with the results of a study from 1104 HIV-infected patients in 2006–2011.Results and discussion. Monovariants of HIV dominated in the examined patients (95.1%, 275 people), subtype A6 — 88.2% (255 people); subtype B — 5.9% (17 people); C — 0.3% (1 person); G — 0.7% (2 people), the proportion of recombinant forms — 4.9% (14 people). In the sample collection, the proportion of new HIV cases of non-A subtype was 13.3% in 2006–2011, and 11.1% in 2018–2022. A significant increase in the incidence of recombinant forms of HIV-1 was revealed from 1.6% to 3.5% (c2=6.111; p=0.014). In the group (2018–2022), the recombinant form of CRF63_02A6 was more common (15/29 people).Conclusion. Phylogenetic analyses makes it possible to determine HIV subtypes, but also to establish the potential geographical origin of the virus, to identify transmission clusters taking into account the socio-demographic indicators of HIV-infected patients. Molecular epidemiological monitoring can be used to develop and implement programs to counter the spread of HIV among the population. The dominant genetic variant of HIV circulating in St. Petersburg is sub-subtype A6, as it was 10 years ago. The proportion of new cases of infection with non-A subtype of HIV remains stable, with a downward trend. The increase in the frequency of detection of recombinant forms of HIV-1 is probably related to the migration processes of the population.

An L-type calcium channel blocker nimodipine exerts anti-fibrotic effects by attenuating TGF-β1 induced calcium response in an in vitro model of thyroid eye disease

BackgroundThyroid eye disease (TED) is a vision-threatening autoimmune disorder. Orbital tissue fibrosis leading to intractable complications remains a troublesome issue in TED management. Exploration of novel therapeutic targets and agents to ameliorate tissue fibrosis is crucial for TED. Recent work suggests that Ca2+ signaling participates in tissue fibrosis. However, whether an alteration of Ca2+ signaling has a role in fibrogenesis during TED remains unclear. In this study, we aimed to investigate the role of Ca2+ signaling in the fibrogenesis process during TED and the potential therapeutic effects of a highly selective inhibitor of the L-type calcium channel (LTCC), nimodipine, through a TGF-β1 induced in vitro TED model.MethodsPrimary culture of orbital fibroblasts (OFs) were established from orbital adipose connective tissues of patients with TED and healthy control donors. Real-time quantitative polymerase chain reaction (RT-qPCR) and RNA sequencing were used to assess the genes expression associated with LTCC in OFs. Flow cytometry, RT-qPCR, 5-ethynyl-2′-deoxyuridine (EdU) proliferation assay, wound healing assay and Western blot (WB) were used to assess the intracellular Ca2+ response on TGF-β1 stimulation, and to evaluate the potential therapeutic effects of nimodipine in the TGF-β1 induced in vitro TED model. The roles of Ca2+/calmodulin-dependent protein kinase II (CaMKII) and signal transducer and activator of transcription 1 (STAT1) in fibrogenesis during TED were determined by immunohistochemistry, WB, flow cytometry and co-immunoprecipitation assay. Selective inhibitors were used to explore the downstream signaling pathways.ResultsLTCC inhibitor nimodipine blocked the TGF-β1 induced intracellular Ca2+ response and further reduced the expression of alpha-smooth muscle actin (α-SMA), collagen type I alpha 1 (Col1A1) and collagen type I alpha 2 (Col1A2) in OFs. Besides, nimodipine inhibited cell proliferation and migration of OFs. Moreover, our results provided evidence that activation of the CaMKII/STAT1 signaling pathway was involved in fibrogenesis during TED, and nimodipine inhibited the pro-fibrotic functions of OFs by down-regulating the CaMKII/STAT1 signaling pathway.ConclusionsTGF-β1 induces an LTCC-mediated Ca2+ response, followed by activation of CaMKII/STAT1 signaling pathway, which promotes the pro-fibrotic functions of OFs and participates in fibrogenesis during TED. Nimodipine exerts potent anti-fibrotic benefits in vitro by suppressing the CaMKII/STAT1 signaling pathway. Our work deepens our understanding of the fibrogenesis process during TED and provides potential therapeutic targets and alternative candidate for TED.

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].

Claisen Self-Condensation of Lactones in the Synthesis of Ionizable Lipids.

The Claisen self-condensation of lactones can be carried out safely and efficiently under Mukaiyama conditions, in the presence of TiCl4 and triethylamine. The primary Claisen products can be elaborated to various derivatives or converted directly into dihydroxyketones. Such compounds are valuable educts for the synthesis of ionizable lipids for the delivery of nucleic acid therapeutics and can now be accessed through a concise, economical, scalable route that avoids more technically challenging reaction sequences.

Non‐Isocyanate Synthesis of Covalent Adaptable Networks Based on Dynamic Hindered Urea Bonds: Sequential Polymerization and Chemical Recycling

AbstractThe development of environmentally sustainable processes for polymer recycling is of paramount importance in the polymer industry. In particular, the implementation of chemical recycling for thermoset polymers via covalent adaptable networks (CANs), particularly those based on the dynamic hindered urea bond (HUB), has garnered intensive attention from both the academic and industrial sectors. This interest stems from its straightforward chemical structure and reaction mechanism, which are well‐suited for commercial polyurethane and polyurea applications. However, a substantial drawback of these CANs is the requisite use of toxic isocyanate curing agents for their synthesis. Herein, we propose a new HUB synthesis pathway involving thiazolidin‐2‐one and a hindered amine. This ring‐opening reaction facilitates the isocyanate‐free formation of a HUB and enables sequential reactions with acrylate and epoxide monomers via thiol–Michael and thiol–epoxy click chemistry. The CANs synthesized using this methodology exhibit superior reprocessability, chemical recyclability, and reutilizability, facilitated by specific catalytic and solvent conditions, through the reversible HUB, thiol–Michael addition, and transesterification processes.

K3PO4–Mediated Synthesis of Chromeno–[3,4‐c]isoxazole from 3–Nitro–2H–chromene and α–Chloro Aldehyde via Michael Addition/C−Cl Bond Cleavage/Deformylation as Key Fragmentation Sequences

AbstractHere we report a transition metal– and oxidant–free annulation cascade method for the synthesis of chromeno–isoxazoles. The annulation reaction involves easily accessible starting materials, 3‐nitro‐2H‐chromene and α‐chloro aldehyde, yielding the structurally intriguing framework, chromeno[3,4‐c]isoxazoles employed by tripotassium phosphate as a base. The isoxazole ring construction over the 2H–chromene unit is believed to occur via a series of multiple reaction sequences. Here, the enolate generation/Michael addition/C−Cl bond cleavage/oxy–anionic addition to reactive tethered‐aldehyde/deformylation via retro–C−C and N−O bond cleavages are the most possible sequences which furnish the desired end–product in good chemical yields. The multiple reaction sequences occur in one‐pot at mild conditions, supported by experimental results and a few control experiments including DFT studies. This process exhibits a broad substrates scope illustrating good functional group compatibility towards both the nitrochromenes and aldehydes, and thus prove to be a general and efficient protocol for the synthesis of chromeno[3,4–c]isoxazoles. Overall, the use of nitrochromene as the limiting reagent, noteworthy functional group tolerance, scalability including great applications like chiral pool strategy towards the synthesis of enantioenriched chromeno‐isoxazole are the additional features.

Intracluster reaction dynamics of NO+(H2O)n.

Nitric oxide (NO) and NO-water clusters play crucial roles in the D-region of the atmosphere because it is postulated that NO+ reacts with H2O to produce nitrous acid (HONO) and H3O+. HONO is the major precursor of the hydroxyl radicals leading to the formation of secondary pollutants. The sources of atmospheric HONO, however, are not fully understood. Previously, the sequential H2O addition reaction, H2O + NO+(H2O)n, and the bi-molecular collision reaction, NO+ + (H2O)n, have been investigated by both experiments and theoretical calculations to determine the formation mechanism of HONO. However, the photo-reactions from NO(H2O)n neutral clusters were not considered for the formation mechanism of HONO. In this study, the intra-cluster reactions of NO+(H2O)n clusters, following ionization of the parent neutral cluster of NO(H2O)n, were investigated using the direct abinitio molecular dynamics method. When n = 4, [NO+(H2O)4]ver [vertical ionization state of NO(H2O)n] yielded HONO and hydrated H3O+ after the intra-cluster reaction, and the reaction time was calculated to be 150fs. The reaction is expressed as [NO+(H2O)n]ver → HONO + H3O+(H2O)n-2 (reactive) (n > 3). Larger clusters of [NO+(H2O)n]ver (n = 5-8) also yield HONO. In contrast, in smaller clusters (n = 1-3), only solvent re-orientation around NO+ occurred after the ionization: [NO+(H2O)n]ver → NO+(H2O)n (solvent re-orientation) (n = 1-3). The hydration energy of H3O+, which depends on the cluster size (n), plays an important role in promoting the formation of HONO. The reaction mechanism is discussed based on theoretical results.

Catalytic Enantioselective Synthesis of Inherently Chiral Calix[4]arenes via Sequential Povarov Reaction and Aromatizations

AbstractInherently chiral calix[4]arenes represent a unique type of chiral molecules with significant applications, yet their catalytic enantioselective synthesis remains largely underexplored. We report herein the catalytic enantioselective synthesis of inherently chiral calix[4]arenes through the sequential organocatalyzed enantioselective Povarov reaction and aromatizations. The chiral phosphoric acid catalyzed three‐component Povarov reaction involving amino group‐substituted calix[4]arenes, aldehydes and (di)enamides desymmetrized the prochiral calix[4]arene substrates, which was followed by various aromatization methods, resulting in a diverse array of novel quinoline‐containing calix[4]arenes with good yields and high enantioselectivities (up to 75 % yield, 99 % ee). The large‐scale enantioselective synthesis and diverse derivatizations of the chiral calix[4]arene products highlight the value of this method. Furthermore, preliminary exploration into their photophysical and chiroptical properties demonstrate the potential applications of these novel calix[4]arene molecules.

De- and Rearomatisation of Pyridine in Silylene Chemistry.

Traditional methods relying on metal-ligand cooperation for activating pyridine bonds in de- and rearomatisation are being challenged by the abundant metal-free element species as alternatives. Here, we investigated the de/re-aromatisation of pyridine facilitated by pyridylamino-functionalised silylene reactions with ketones and ketene. The reactivity outcome is highly dependent on the substituents on the ketones. By carefully tuning the steric demand of the ketone, each intermediate of the reaction sequence could be isolated. At room temperature, benzophenone and acetophenone substrates led to dearomatisation of the pyridine moiety, with the case of acetophenone showing an intermediate silaoxirane preceding dearomatisation. However, when subjected to acetone or diphenylketene, only silaoxiranes were formed without dearomatisation of the pyridine moiety. Notably, only benzophenone-derived dearomatised species demonstrated rearomatisation upon heating. Furthermore, the reduced steric bulk of the ketene facilitated further ring expansion with another equivalent of the substrate, forming sila-1,3-dioxolanes. Both steric hindrance and aromatic groups collectively influence the dearomatisation of pyridine in pyridylaminosilylene reactions.