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The arranged paths of dominoes have many shapes. The scaling law for the propagation speed of domino toppling has been extensively investigated. However, in all previous investigations the scaling law for the velocity of domino toppling motion in curved lines was not taken into account. In this study, the finite-element analysis (FEA) program ABAQUS was used to discuss the scaling law for the propagation speed of domino toppling motion in curved lines. It is shown that the domino propagation speed has a rising trend with increasing domino spacing in a straight line. It is also found that domino propagation speed is linearly proportional to the square root of domino separation. This research proved that the scaling law for the speed of domino toppling motion given by Sun [Scaling law for the propagation speed of domino toppling. AIP Adv. 2020;10(9):095124] is true. Moreover, the shape of domino arrangement paths has no influence on the scaling law for the propagation speed of dominoes, but can affect the coefficient of the scaling law for the velocity. Therefore, the amendatory function for the propagation speed of dominoes in curved lines was formulated by the FEA data. On one hand, the fitted amendatory function, φ revise {\varphi }_{{\rm{revise}}} , provides the simple method for a domino player to quickly estimate the propagation speed of dominoes in curved lines; on the other hand, it is the rationale for the study of the domino effect.

An efficient and facile method for the regioselective synthesis of novel dihydrobenzo[a]fluorenes from readily accessible alkynols is presented. The current strategy triggers the formation of a dual C-C bond intramolecularly via Lewis acid catalysis under mild reaction conditions. Notably, secondary as well as tertiary alcohols bearing an alkyne moiety have been smoothly transformed into the corresponding products. As a result, novel tetracyclic dihydrobenzo[a]fluorenes have been accomplished using this approach.

With progressing global warming, there is an increased risk that one or several tipping elements in the climate system might cross a critical threshold, resulting in severe consequences for the global climate, ecosystems and human societies. While the underlying processes are fairly well-understood, it is unclear how their interactions might impact the overall stability of the Earth's climate system. As of yet, this cannot be fully analysed with state-of-the-art Earth system models due to computational constraints as well as some missing and uncertain process representations of certain tipping elements. Here, we explicitly study the effects of known physical interactions among the Greenland and West Antarctic ice sheets, the Atlantic Meridional Overturning Circulation (AMOC) and the Amazon rainforest using a conceptual network approach. We analyse the risk of domino effects being triggered by each of the individual tipping elements under global warming in equilibrium experiments. In these experiments, we propagate the uncertainties in critical temperature thresholds, interaction strengths and interaction structure via large ensembles of simulations in a Monte Carlo approach. Overall, we find that the interactions tend to destabilise the network of tipping elements. Furthermore, our analysis reveals the qualitative role of each of the four tipping elements within the network, showing that the polar ice sheets on Greenland and West Antarctica are oftentimes the initiators of tipping cascades, while the AMOC acts as a mediator transmitting cascades. This indicates that the ice sheets, which are already at risk of transgressing their temperature thresholds within the Paris range of 1.5 to 2 ∘C, are of particular importance for the stability of the climate system as a whole.

We herein report an unprecedented photoinduced cyclization/defluorination domino process of N-allylbromodifluoroacetamide with cyclic secondary amines. Consequently, a wide array of valuable 3-fluoro-1,5-dihydro-2H-pyrrol-2-ones were facilely prepared from readily available starting materials under mild conditions. Preliminary mechanistic investigations suggest that a radical chain propagation and amine-promoted defluorination pathway are presumably involved in this transformation.

Virtually inert sulfur hexafluoride becomes a precious pentafluorosulfanylation agent, if properly activated by photoredox catalysis, to access α-fluoro and α-alkoxy SF5-compounds. This advanced protocol converts SF6 in the presence of alkynols as bifunctional C−C- and C−O-bond forming reagents directly into pentafluorosulfanylated oxygen-containing heterocycles in a single step from α-substituted alkenes. The proposed mechanism is supported by theoretical calculations and gives insights not only in the pentafluorosulfanylation step but also into formation of the carbon-carbon bond and is in full agreement with Baldwin's cyclization rules. The key step is a radical type 5-, 6- respectively 7-exo-dig-cyclization. The synthesized oxaheterocycles cannot be simply prepared by other synthetic methods, show a high level of structural complexity and significantly expand the scope of pentafluorosulfanylated building blocks valuable for medicinal and material chemistry. ISSN:0947-6539 ISSN:1521-3765

Palladium-catalyzed C-N bond formation is one of the widely used transformations for the synthesis of structurally diverse N-heterocycles. This work describes an efficient palladium-catalyzed multiple-C-N bond formation reaction for the synthesis of highly π-conjugated N-heterocycles, indolo[3,2-b]indoles with di-tert-butyldiaziridinone. The reaction likely proceeds through the initial formation of an indole-fused palladacycle by nucleophilic aminopalladation and subsequent bisamination to give indolo[3,2-b]indoles.

Substituted 2,6-dicyanoanilines are versatile electron donor-acceptor compounds, which have recently received considerable attention, since they exhibit strong fluorescence and may have utility in the synthesis of fluorescent materials, non-natural photosynthetic systems, and materials with nonlinear optical properties. The majority of known synthetic procedures are, however, "stop-and-go" reaction processes involving time-consuming and waste-producing isolation and purification of product intermediates. Here, we present the synthesis of substituted 2,6-dicyanoanilines via atom-economical and eco-friendly one-pot processes, involving metal-free domino reactions, and their subsequent photochemical and photophysical measurements and theoretical calculations. These studies exhibit the existence of an easily tunable radical ion pair-based charge-transfer (CT) emission in the synthesized 2,6-dicyanoaniline-based electron donor-acceptor systems. The charge-transfer processes were explored by photochemical and radiation chemical measurements, in particular, based on femtosecond laser photolysis transient absorption spectroscopy and time-resolved emission spectroscopy, accompanied by pulse radiolysis and complemented by quantum chemical investigations employing time-dependent density-functional theory. This chromophore class exhibits a broad-wavelength-range fine-tunable charge recombination emission with high photoluminescence quantum yields up to 0.98. Together with its rather simple and cost-effective synthesis (using easily available starting materials) and customizable properties, it renders this class of compounds feasible candidates as potential dyes for future optoelectronic devices like organic light-emitting diodes (OLEDs).

An efficient visible light mediated photocatalyst free C-S cross-coupling reaction has been developed for the synthesis of thiochromane derivatives through photoinduced electron transfer (PET). This methodology was further utilized for the synthesis of thiochroman-4-ol through intermolecular three-component cross-coupling reaction. The reaction proceeds via C-S bond formation through EDA complex/thioester cleavage/inter-or intramolecular

A straightforward domino approach to assemble benzoxazole-derived sulfonamides has been developed. The method is based on annulation-induced in situ generation of diazo compounds from readily available 2-(5-iodo-1,2,3-triazolyl)phenols, followed by metal-free denitrogenative transformation upon the action of 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) (DABSO) and amines. The protocol is operationally simple and features a broad substrate scope, furnishing a library of target compounds in generally good yields.

A simple InBr3-catalyzed domino reaction of indoles, phenylacetylenes, and various 3-methyleneoxindolines in toluene is described. This reaction not only provided a convenient synthetic protocol fo...

Domino effects are typically high-impact low-probability (HILP) accidents, which pose a serious threat to chemical process industries. Previous researches on domino effects in chemical industries focus more on static analysis at the spatial scale. From the perspective of the spatial and temporal characteristics of the accident, this study proposed a model to analyze dynamic evolution process of domino effects by using matrix calculation coupled with Monte Carlo simulation, and the dynamic propagation of pool fire accidents is considered as the evolution of domino effects. The algorithm of the model for dynamic domino probabilities considering the synergistic effects of multiple escalation vectors from different units can be used to analyze the complex scenarios of domino effects with high-level and multiple primary accident units. Moreover, the model can be applied in chemical areas with a large number of installations due to the greatly improved calculation efficiency. The proposed model is tested and validated using earlier studied dynamic Bayesian network method, and the application of the model is demonstrated on a complex multi-unit system. The results show that domino effects have strong temporal correlation, and the scenario with multiple primary accident units is much more serious than that with only one primary accident unit, which provide important support for the implementation of emergency response. The study highlights that the proposed model serves as an important tool to evaluate strategies for prevention and control of domino effects.

In this paper, an optimisation-based approach to obtain safe multi-floor process plant layout designs using the domino hazard index (a sub-index of the integrated inherent safety index) is presented. A mixed integer linear programming (MILP) model is proposed to obtain the economically optimal multi-floor layout design considering connection by pipes, horizontal and vertical pumping of process fluids, purchase of land, fixed and area-dependent construction of floors, the financial risk associated with hazardous events and their escalation potential, and the installation of passive protection devices. Hazardous events such as pool fires, jet fires, flash fires, fireballs and blast waves resulting from explosions are considered using a novel and more realistic estimation of safety distances between equipment items. A bi-objective optimisation problem is also considered, minimising the layout costs and the total domino hazard index values for the plant, adopting the ϵ -constraint method. The proposed model is then applied to an 11-unit case study susceptible to each of these hazardous events, obtaining results with the optimal layout and protection device configurations in a relatively short amount of time.

The explosion load is a significant escalation factor possibly influencing the potential occurrence of domino accidents in chemical plants. It is not economical to install explosion isolation systems (e.g., extinguishing barrier) for all equipment or process units across a chemical plant. Although shutting down all equipment or process unit can prevent an explosion, it may also cause further economic losses. To prevent domino accidents, the process unit that needs to be shut down accurately should be selected, and the normal operation of other units needs to be ensured. A method to select the process unit to be isolated based on the Dimensioning Accidental Load (DAL) is proposed. By calculating the occurrence probability and consequences of the accident scenarios, the DAL of the surrounding units is determined. DAL is used as the impact intensity of the accident unit on the surrounding units. The probit model is used to calculate the damage probability of surrounding units. The case analysis results show that the method of selecting the process unit to be isolated based on DAL quantifies the impact intensity of the exploded unit on surrounding units from probability and consequence. Under the premise of meeting the acceptable risk criteria, the method can determine which units should be shut down and which units can operate normally when a release accident occurs. While preventing domino accidents, economic losses caused by the shutdown of all process units are reduced and a theoretical basis for accident prevention and safe operation of the plant is provided. (C) 2021 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

In this article, a novel long-distance wireless power transfer (WPT) system that achieves excellent constant current (CC) output based on a domino-resonator is proposed. A thorough mathematical model of the n-coil domino WPT system is established, and the methodology of calculating and choosing the operating frequency in the CC mode is put forward to achieve high efficiency and the best stability. The zero-phase-angle (ZPA) condition is proven to be realized, in the meantime, by theoretical derivation. The phenomenon that operating frequency slightly shifts away from the resonant frequency in the CC mode due to the magnetic coupling between nonadjacent coils is studied. The efficiency of the system is evaluated. Moreover, system efficiency can be further improved by optimizing the number of coils and layers when the transfer distance is fixed. An experimental setup with an output current of 0.6 A has been built to demonstrate the validity of the proposed system. The experimental results show that the maximum system efficiency of the experimental setup in the CC mode can achieve 70% at the transfer distance of 0.7 m when the number of the coils is 8 and the radius of the coil is 100 mm.

An efficient method for the synthesis of highly substituted bicyclic pyridone derivatives containing the dithiocarbamate group is reported via a one-pot three-component reaction of 2-(alkylthio)thio­azlactones, diamines, and nitroketene dithioacetal in EtOH under catalyst-free conditions. The reaction proceeds via a domino amidation–­intramolecular 1,4-addition-type Friedel–Crafts alkylation reaction to afford the corresponding fused bicyclic pyridones with high yields and diastereoselectivity.

A p-TsOH-mediated one-pot, three-component methodology has been developed for the synthesis of pyrrolo/indolo[1,2-a]quinoxalines substituted with o-biphenylester/N-arylcarbamate/N-arylurea at the C-4 position under open-air heating conditions. The protocol offers a transition-metal-free and external oxidant-free solvent-mediated pathway to afford a library of diversely substituted quinoxalines in moderate to good yields. Various water-miscible aliphatic alcohols and amines participate in the reactions both as solvent as well as reactant. X-ray crystal structure analysis suggests that some of the suitably substituted quinoxalines may exhibit atropisomerism at room temperature.

We disclose herein a Au(I)-catalyzed domino cyclization of 1,6-diynes incorporated with indole. This protocol enabled the diastereoselective buildup of indole-fused azabicyclo[3.3.1]nonanes from linear precursors. Density functional theory calculations showed that the reaction proceeded via an unprecedented cascade dearomatization/rearomatization/dearomatization process. Independent gradient model analysis revealed that a noncovalent attractive interaction between the distal alkyne and the Au/proximal complex was responsible for the chemoselectivity of the first spirocyclization step.

N-Heterocyclic carbene-catalyzed tandem Stetter-aldol reaction of phthalaldehyde and α,β-unsaturated ketimines has been developed to afford functionalized naphthalen-1(2H)-one derivatives as the formal [4+2] annulation product. Interestingly, the reaction of aldimines led to the formation of isoquinoline derivatives instead of the expected indanone derivatives as a [4+1] annulation product.

Flood events impose great distress on chemical industrial areas, since they may cause Natech accidents involving multiple units. Furthermore, escalation vectors exerted by major accidents can trigger knock-on events, so-called domino effects, causing very severe consequences. In the present study, a methodology is proposed to include domino effects triggered by floods in a quantitative risk assessment, by addressing the frequency assessment of flood-induced domino scenarios. A comprehensive procedure is developed, combining the fragility model for unit damage due to floods, probability estimation for domino escalation, and combinatorial analysis for overall scenarios. Moreover, the flow interference due to the layout of chemical industrial areas is explored to calculate the damage probability more accurately. The methodology has been demonstrated by a case study, the changes in risk indexes and damage zones due to Natech domino effects are discussed. The results show that the overall risk significantly increases with respect to conventional scenarios when considering flood-induced Natech events and domino effects, evidencing the importance of risk analysis of Natech-related domino effects. Finally, some prevention measures have been proposed for chemical industrial areas to make them more resilient and safer when it comes to floods. (C) 2021 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

Domino reactions involving nickel‐catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary‐alcohol‐containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti‐arylmetallative cyclization to occur. The ring system of the products are substructures of certain diarylindolizidine alkaloids.

A domino annulation/oxidation of heterocyclic ketene aminals (HKAs) and 2-aminochalcones has been developed for the selective synthesis of poly-substituted benzo[f]imidazo[2,1-a][2,7]naphthyridines and 3-azaheterocyclic substituted 2-arylquinolines. These reactions proceed well under mild conditions without any additives. Plausible mechanisms for such a polycyclic ring system assembly were also proposed. Moreover, benzo[f]imidazo[2,1-a][2,7]naphthyridine 3g displayed a fluorescence effect, demonstrating the potential applications in organic optical materials.

A novel synthesis of 2,3-substituted benzothiophenes is reported, involving a tandem base-mediated condensation of o-iodoarylacetonitriles/acetates/ketones with (hetero)aryldithioesters and an intramolecular C-S bond formation. The reaction affords diversely substituted benzothiophenes and heterofused thiophenes in excellent yields.

The intramolecular Diels-Alder reactions of helicenes deform their π-conjugated screw-shaped skeletons. In particular, terminally tetrafluorinated [7]helicene (F4 -[7]helicene) undergoes a photoinduced Diels-Alder reaction followed by a photoinduced double fluorine atom transfer. Herein, we thoroughly investigated this photochemical domino process by decreasing the level of fluorine substitution. F3 -[7]Helicenes bearing two fluorine atoms at the dienophile terminal underwent photoinduced Diels-Alder reactions, but the whole domino process became slow. F2 -[7]Helicene, which is difluorinated only at the dienophile terminal, was also photolabile. As a result, two fluorine atoms were sufficient for the photochemical domino reaction to occur. X-ray crystallographic analysis revealed that F2 -[7]helicene was less compressed than F4 -[7]helicene, indicating that terminal polyfluorination enhanced the intramolecular arene-fluoroarene stacking interactions and thus promoted the transformations.

This report describes the total synthesis of the complex, oxygenated tetracyclic alkaloid, lyconesidine B. The key synthetic challenge involves diastereoselective generation of a decahydroquinoline ring with a quaternary carbon at the angular position via domino cyclopropanation, ring-opening, and reduction. Another crucial step is the domino ene-yne metathesis involving a quaternary ammonium ion, leading to the construction of a decahydroazaazulen framework.

Due to complexities and uncertainties, risk management of domino effects in chemical plants in operation is challenging. A global optimal risk management scheme can hardly be obtained, therefore, finding a targeted local optimal risk management scheme can be prudent. In the present study, a novel risk management approach is proposed to reduce fire-induced domino effect risk by leveraging loading/unloading demands based on risk aggregation and inventory management. The proposed approach uses the aggregation of three risk indicators as part of the risk management strategy. The first risk indicator is the loss of containment (LOC) risk of chemical installations, which indicates how likely a storage tank may cause a primary fire accident. The second risk indicator is the secondary fire accident inducing ability of chemical installations, which indicates how likely a primary tank may cause secondary fire accidents only. The third risk indicator is the inter-unit closeness degree of chemical installations, which indicates how severe the overall consequence a primary tank may cause. Combining the aggregate risk with the inventory availability of storage tanks, candidate risk management schemes are proposed based on inventory management on chemical loading/unloading demands. The optimal risk management scheme is determined based on the potential losses of fire-induced domino effects. A case study demonstrates the effectiveness of the proposed methodology and risk management strategy for fire-induced domino effects.

Considering wind-speed influence, a new acceleration model is established, and a trajectory equation is obtained. The impact-depth models of a cone and end-cover debris are also established based on the cavity expansion theory. Combined with the residual strength theory, a new spherical-tank failure-probability model is established, and the probability model of a domino accident caused by the debris is obtained. Additionally, the influence of different fragment shapes on the domino accident probability in spherical tanks is analysed, and minimum penetration rate of the spherical-tank failure caused by different fragment masses is calculated. Subsequently, using statistics, the correlation between failure-probability and distance between spherical tanks and shape parameters was determined. The results indicate that the debris shape significantly influences the impact-depth of the spherical-tank wall, and impact-depth of the conical-nose geometry is significantly greater than that of the blunt-nose geometry. Moreover, the minimum velocity of the conical-nose geometry penetrating the target is significantly less than that of the blunt-nose geometry. The shape change of the conical-nose geometry has almost no influence on the probability of the domino accident, whereas, that of the blunt-nose geometry significantly influences the domino accident probability.

In this study, the domino Knoevenagel-Michael and cyclization reaction between 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and aryl aldehydes was performed in the presence of sulfacetamide as an o...

The electrochemical three‐component assembly of isoquinolines has been accomplished by ruthenaelectro‐catalyzed C−H/N−H functionalization. The robustness of the electrocatalysis was reflected by an ample substrate scope, an efficient electrooxidation, and an operationally friendly procedure. The isolation of key intermediates and detailed mechanistic studies, including unprecedented cyclovoltammetric analysis of a seven‐membered ruthenacycle, provided support for an unusual ruthenium(II/III/I) regime., Ruthenium‐catalyzed electrooxidative three‐component syntheses of isoquinolines proved viable with ample scope. The isolation of key intermediates, along with DFT calculations revealed an unusual ruthenium(II/III/I) catalytic cycle.

An unprecedented nickel-catalyzed domino reductive cyclization of alkynes and o-bromoaryl aldehydes is described. The reaction features broad substrate scope and is tolerant of a variety of functional groups, providing a straightforward access to biologically significant indanones and spiro-indanone pyrrolidine derivatives in good yields with excellent regio- and diastereoselectivity. Preliminary mechanistic studies have shown that indanones are formed by the cyclization of o-bromoaryl aldehydes and alkynes to form indenol intermediates, followed by hydrogen autotransfer.

A metal‐free oxidative [3+1+1] convergent domino annulation has been developed for the synthesis of 2,4,5‐trisubstituted oxazoles. Compared with existing methods, this method has the advantages of wide substrate scope, mild reaction conditions, and obtaining raw materials.

The reaction of β-ketonitrile and N-substituted pyrrole-2-carboxaldehyde in the presence of piperidinium acetate in CH3CN permitted regioselective access to 5-acylindolizine-7-carbonitrile through a domino Knoevenagel condensation–intramolecular aldol cyclization sequence. A wide range of new indolizine derivatives with a poly-functionalized pyridine moiety were readily synthesized in an atom-economical fashion, thereby expanding the indolizine chemical space for further applications.

The copper-catalyzed cascade cyclization of 2-haloaryl isoselenocyanates with isocyanides to access benzo[d]imidazo[5,1-b][1,3]selenazoles has been realized efficiently under ligand-free conditions. The less commonly developed isoselenocyanates served as the selenium sources for the preparation of a new class of selenium-containing heterocyclic compounds. This protocol was designed to involve sequential intermolecular [3 + 2] cycloaddition and intramolecular Ullmann-type C–Se bond formation.

A Pd(ii)/Cu(ii) catalysed domino synthesis of tricyanovinylindoles has been achieved using DMSO as a one-carbon synthon. The reaction proceeds via the construction of 2-aryl-3-formyl indole followed by sequential addition of malononitrile and a CN resulting in two C-C, one C[double bond, length as m-dash]C and one C-N bonds in the final product. Furthermore, post-synthetic modification results in the unprecedented formation of 4-cyano-3-indolylmaleimides. Photophysical studies of selected compounds show emission in the visible range.

A facile and efficient synthesis of 7-iodobenzo[b]furan derivatives via a highly regioselective tandem α-arylation/intramolecular O-arylation of 5-substituted-1,2,3-triiodobenzenes and benzylketones is described. Remarkably, the α-arylation coupling reactions initiate exclusively at the least sterically-hindered position of the triiodoarene, which results in a highly chemoselective transformation. The highest yields were observed in reactions between electron-poor 1,2,3-triiodoarenes and electron-rich benzylketones, yet the optimized reaction conditions were found to be tolerant to a wide range of different functional groups. This unprecedent synthesis of 7-iodobenzo[b]furans from 1,2,3-triiodobenzenes is scalable, general in scope, and provides easy access to valuable precursors for other chemical transformations.

An efficient Pd-catalyzed domino Mizoroki–Heck and reductive Heck reaction of terminal alkenes with six-membered cyclic diaryliodoniums is reported for the facile access to a diverse set of novel dihydroanthracenes. The scope of alkenes is general, leading to concise generation of 30 dihydroanthracenes which are not easily accessed by conventional methods. Furthermore, one of the newly synthesized dihydroanthracene displayed excellent antiproliferative activity against PANC-1 cancer cells (IC50 = 11.74 μM).

A simple and practical domino protocol for the selective synthesis of 2-aroylbenzothiazoles and 2-aryl benzothiazoles catalyzed by I2 is developed under metal-free conditions. The reaction outcomes are exclusively controlled by the reaction oxidant/medium. With DMSO employed as both the solvent and the oxidant, an oxidation of aromatic methyl ketones takes precedence over the condensation with 2-aminobenzenethiols. On the other hand, when the reaction was carried out in PhNO2 or in 1,4-dioxane containing PhNO2, the condensation of aromatic methyl ketones with 2-aminobenzenethiols has priority to form imines which is followed by an oxidation of the methyl group from ketones to afford 2-arylbenzothiazoles as a sole product. The PhNO2/I2 co-catalytic system is proposed first time.

A Fe-Mo-Se nanopowder, synthesized by a solvothermal protocol, was utilized as a heterogeneous catalyst for the synthesis of 2-arylquinazolines from DL-α-phenylglycine-based α-amino acids and 2-nitrobenzyl alcohols via domino transformations. High yields and selectivity were achieved under solvent-free conditions. The Fe-Mo-Se catalyst offered considerably higher activity than numerous homogeneous and heterogeneous catalysts. To our best knowledge, this domino reaction is new, and the utilization of iron-molybdenum selenide catalyst in the synthesis of quinazolines was not previously reported.

A domino accident is a typical multi-hazard coupling disaster in the chemical industry that often has serious consequences and social impact. The quantitative risk assessment of domino accidents faces several difficulties caused by their complexity, unpredictability, and synergic effects. This paper proposes a new method for quantitative risk assessment of domino accidents in the chemical industry based on field theory and Monte Carlo simulation. The method is intended to obtain the dynamic distribution of the individual risk caused by the domino accident. Monte Carlo simulation is used to account for all accident scenarios and to calculate the average risk distribution. The application of field theory enables the consideration of the synergic effects. To evaluate the efficacy of the assessment method, a typical domino scenario in a chemical plant in Yancheng, China, is taken as a case study. The results show that domino accidents consist of three stages: rapid development stage, stabilization stage, and weakening stage. The risks of fire, explosion, and toxic releases also have different distribution characteristics: flat, peak, and slope. The results also show that the risk of domino accidents increases due to the synergic effects of physical effects and human vulnerability. The new risk assessment method can provide guidance for the prevention, mitigation, and risk management of domino accidents in the chemical industry.

A highly efficient synthetic route to polysubstituted 2H-chromenes was developed utilizing a domino O-alkylation/intramolecular Horner–Wadsworth–Emmons (HWE) olefination of diarylmethylphosphonates, which were readily accessed via Lewis acid mediated one-pot three-component coupling of aldehydes, phenols, and triethyl phosphite.

Here we report a detailed theoretical study of the mechanism of Cu+-catalyzed domino rearrangement of 2-methyl-N-methoxyaniline with a deep understanding of the unique motivation and selectivity of these migrations. We find that the Cu+ catalyst accelerates the [1,3]-methoxy migration to the methyl-bound ortho position of umpolung phenyl. The following domino transfer prefers methyl [1,2]-migration, and the rate-determining step for the whole reaction is the transfer of a proton from the phenyl ring to amine to finish the catalytic cycle.

A solid amino‐supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne‐substituted cyclopentenol compounds. This heterogeneous catalyst exhibits high efficiency and excellent chemoselectivity, as well as good recyclability. The chemoselectivity of the domino reactions was readily controlled by switching the solvent and catalyst. Asymmetric syntheses and an oxidative carbocyclization‐borylation reaction have also been developed based on the heterogeneous palladium catalyst., An oxidative domino reaction is developed here for the construction of alkyne‐substituted cyclopentenol compounds by using an amino‐supported Pd catalyst. The properties of the heterogeneous catalyst contribute to its high efficiency and excellent chemoselectivity, as well as good recyclability.

A novel polyheterocyclic chemical space, 6H-furo[3,2-f]pyrrolo[1,2-d][1,4]diazepine, was generated by a one-pot four-component coupling reaction where multiple bonds (three C-C, one C-O, and one C-N) were formed through a domino sequence. Two heterocyclic rings (furan and diazepine) were sequentially constructed from the monocyclic pyrrole derivative under environment-friendly reaction conditions to furnish the tricyclic fused scaffold.

It is often said that "time is money". This is certainly true in a multistep synthesis when a high-valued product or set of products is needed urgently. Fulfilling this need requires the sensible balancing of atom economy, step economy, and redox economy with the time taken to make the product. In this age of flu-based pandemics, the need for rapid provision of effective therapeutic agents makes the importance of "time economy" particularly clear. In this Perspective, the importance of time economy in total synthesis is described, as well as the general considerations underlining the timely production of desired molecules. As case studies, the syntheses of Tamiflu, Corey lactone, and ibuprofen are discussed, with emphasis on comparing classical and contemporary approaches to a rapid total synthesis. By using modern tactics such as one-pot reaction procedures and versatile synthetic methodologies such as organocatalyst mediated domino reactions coupled with strict-control technologies such as flow chemistry, Tamiflu and Corey lactone can now be synthesized within 60 and 152 min, respectively, using one vessel via a batch system. Tamiflu and ibuprofen can be prepared via flow system, and their total residence times are 11.5 and 3 min, respectively.

A palladium-catalyzed domino process for the quick assembly of tricyclic-fused heterocycles starting from aryl iodides and functionalized isocyanides containing a disubstituted terminal alkene has been developed. The process is triggered by intermolecular isocyanide insertion, followed by Heck-type carbopalladation of the intramolecular alkene moiety and subsequent C(sp2)-H activation. Moreover, an asymmetric version of this reaction could also be realized in good yield with moderate enantioselectivity after preliminary exploration of chiral ligands.

Pd-catalyzed annulative couplings of 2-alkenylanilines with aldehydes using alcohols as both the solvent and hydrogen source have been developed. These domino processes allow divergent syntheses of two significant N-heterocycles, indoles and quinolines, from the same substrate by tuning reaction parameters, which seems to invoke two distinct mechanisms. The nature of the ligand and alcoholic solvent had a profound influence on the selectivity and efficiency of these protocols. Particularly noteworthy is that indole formation was achieved by overcoming two significant challenges, regioselective hydropalladation of alkenes and subsequent reactions between the resulting Csp3-Pd species and less reactive imines.

We report the synthesis of 4-(furan-2-yl)-3,4-dihydro-2H-pyrrol-2-one derivatives. In this approach, two core structures, the furan ring and 3,4-dihydro-2H-pyrrol-2-one, are constructed via silver(I)-catalyzed cascade cyclization/cyclopropanation/ring-cleavage/nucleophilic substitution reaction of enynones with enamines. A reasonable mechanism has been proposed. This method possesses some advantages such as high chemoselectivity, mild reaction conditions, simple operation, and short reaction time.

Mechanochemical activation effectively mediated asymmetric organocatalytic domino Mannich addition followed by diastereoselective fluorination. The Mannich reactions of pyrazolones and to a lesser extent those of isoxazolones were effective under solvent-free ball-milling conditions. This reaction in combination with a chiral squaramide catalyst provided corresponding products in high yields and enantiomeric purities up to 99:1 e.r. and as a single diastereomer. DFT calculations revealed reasons for high diastereoselectivity.

An efficient magnetically recyclable bimetallic catalyst by anchoring copper and manganese complexes on the Fe3O4 NPs was prepared and named as Fe3O4@Cu-Mn. It was founded as a powerful catalyst for the domino one-pot oxidative benzimidazole and Biginelli reactions from benzyl alcohols as a green protocol in the presence of air, under solvent-free and mild conditions. Fe3O4@Cu-Mn NPs were well characterized by FT-IR, XRD, FE-SEM, TEM, VSM, TGA, EDX, DLS, and ICP analyses. The optimum range of parameters such as time, temperature, amount of catalyst, and solvent were investigated for the domino one-pot benzimidazole and Biginelli reactions to find the optimum reaction conditions. The catalyst was compatible with a variety of benzyl alcohols, which provides favorable products with good to high yields for all of derivatives. Hot filtration and Hg poisoning tests from the nanocatalyst revealed the stability, low metal leaching and heterogeneous nature of the catalyst. To prove the synergistic and cooperative effect of the catalytic system, the various homologues of the catalyst were prepared and then applied to a model reaction separately. Finally, the catalyst could be filtered from the reaction mixture simply, and reused for five consecutive cycles with a minimum loss in catalytic activity and performance. A new magnetically recyclable Cu/Mn bimetallic catalyst has been developed for domino one-pot oxidation-condensation of benzimidazole and Biginelli reactions from alcohols.

An efficient three-component domino or one-pot strategy has been developed for the synthesis of medicinally important benzothiophene and benzothiopheno[2,3-e]azepinedione derivatives for the first time. Amine-promoted selective cleavage of C-S bond of thioisatin is the key step in this process. The reported methodology benefits from environmentally friendly solvent (H2O), wide substrate scope, good functional group tolerance, and high reaction yields.

The design of transmitting antenna arrays with a modular aperiodic architecture for far-field wireless power transmission (WPT) is addressed in this work. The synthesis of the subarray layout and o...