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Keywords: C-H bond functionalization; fused-ring systems; heteroarenes; homogeneous catalysis; synthetic methods EN C-H bond functionalization fused-ring systems heteroarenes homogeneous catalysis synthetic methods 3526 3534 9 10/19/23 20231102 NES 231102 Graph Pyrazolo[1,5- I a i ]pyrazines are an emerging class of 5,6-fused bicyclic heterocycles that shows huge potential in medicinal chemistry. [22] Nevertheless, the fact that Ag SB 2 sb CO SB 3 sb was more effective than Cs SB 2 sb CO SB 3 sb in the cross-coupling of B 1a b and B 4a b (Table 1) suggested that the silver cation should play a special role. The results showed that both Cs SB 2 sb CO SB 3 sb and Ag SB 2 sb CO SB 3 sb could facilitate H/D exchange of B 1a b at the C7 position. HRMS: I m i / I z i [M + H] SP + sp calcd for C SB 16 sb H SB 13 sb F SB 3 sb N SB 3 sb O SB 3 sb : 352.0909; found: 352.0891. [Extracted from the article]

C7‐Arylated pyrazolo[1,5‐a]azines are important structural motifs with profound applications in drug and material research. Here, we report a general and straighforward synthesis of these bi(hetero)aryls via palladium‐catalyzed direct C−H arylation, employing low‐cost and abundant (hetero)aryl chlorides as the aryl source. The catalytic system is robust and covers a wide substrate scope regarding heteroarenes as well as (hetero)aryl chlorides, with possible extension to the C−H arylation of [1,2,4]triazolo[1,5‐a]pyrimidines. This study also presents a rare example of using (hetero)aryl chlorides for the direct C−H arylation of six‐membered heteroarenes. [ABSTRACT FROM AUTHOR]

Deep generative models have emerged as a powerful class of priors for signals in various inverse problems such as compressed sensing, phase retrieval and super-resolution. In this work, we consider the compressed sensing problem and assume the unknown signal to lie in the range of some pre-trained generative model. A popular approach for signal recovery is via gradient descent in the low-dimensional latent space. While gradient descent has achieved good empirical performance, its theoretical behavior is not well understood. We introduce the use of stochastic gradient Langevin dynamics (SGLD) for compressed sensing with a generative prior. Under mild assumptions on the generative model, we prove the convergence of SGLD to the true signal. We also demonstrate competitive empirical performance to standard gradient descent. [ABSTRACT FROM AUTHOR]

The Annamite mountains of Vietnam and Laos are a global biodiversity hotspot harboring several threatened endemic species. Conservation efforts to protect these endemics are hampered by a lack of knowledge on their ecology and distribution. We conducted landscape scale camera‐trapping across six study areas in the Annamites to assess distribution patterns of two endemics: the Annamite dark muntjac species complex Muntiacus rooseveltorum/ truongsonensis and the Annamite striped rabbit Nesolagus timminsi. We used a Bayesian single‐species occupancy framework to estimate occupancy as a function of ecological and anthropogenic factors. Our study showed that Annamite dark muntjac was predominantly found at higher elevations (>1000 m) and in areas that were more inaccessible to people and had lower surrounding village density. Annamite striped rabbit exhibited both positive and negative responses to elevation among study areas, with no clear response to the anthropogenic covariates. Our results showed that covariate responses varied among the study areas when random effects were included on study areas. We discuss the application of random effects to investigate species occupancies across large spatial scales, and the risk of not accounting for variation among study areas. Our prediction maps provide the first comprehensive overview of the distribution of these endemic species across a substantial part of their range and can be used to help stakeholders focus conservation efforts on priority areas. [ABSTRACT FROM AUTHOR]

The use of Pd(OAc)2 as the catalyst and AgOAc as the oxidant enabled the direct regioselective oxidative C–H/C–H cross-coupling of pyrazolo[1,5-a]pyrimidines or pyrazolo[1,5-a]pyridines with various five-membered heteroarenes without the need of pre-activation and/or directing groups. Successful coupling partners include thiophenes, benzothiophenes, thiazoles, furans, oxazoles, indoles and imidazo[1,2-a]pyridines. [ABSTRACT FROM AUTHOR]

The Delacour's langur (Trachypithecus delacouri) is a critically endangered and endemic primate that inhabits a small region in North Vietnam. While the main threats to the langurs include illegal hunting and habitat destruction, the potential impacts of climate change on this species have never been assessed. In this study, we used Maxent, a species distribution modelling approach that has been shown to be suited for rare species, to assess the effects of climate change on the distribution of the Delacour's langur in different future scenarios. We constructed an optimally tuned model to predict climatically suitable habitat for T. delacouri in current conditions, then projected the models to three future periods, 2041-2060, 2061-2080, and 2081-2100 using data from three general circulation models. Our models showed high predictive performance and successfully predicted the current known range, but also showed areas of overprediction that may reflect a part of the langur's ecology. Our results estimated an overall loss in total suitable habitat, with an average value of approximately -26.97% in the 2041-2060 period, -29.81% in the 2061-2080 period, and -15.48% in the 2081-2100 period, compared to the current predicted range, but they also predicted the currently important Van Long-Kim Bang region as suitable across all future scenarios. We suggest that some of the predicted climatically suitable areas, including Van Long, Kim Bang, Lac Thuy, and Cuc Phuong, may be crucial for future conservation and population re-establishment/re-introduction activities of the Delacour's langur. [ABSTRACT FROM AUTHOR]

Deep neural networks can achieve impressive performance in the regime where they are massively over-parameterized. Consequently, over the past year, there has been a growing interest in analyzing optimization and generalization properties of over-parameterized networks. However, the majority of existing work only applies to supervised learning. The role of over-parameterization in the unsupervised setting has by contrast gained far less attention. In this paper, we study the inductive bias of gradient descent for two-layer over-parameterized autoencoders with ReLU activation. We first provide theoretical evidence for the memorization phenomena observed in recent work using the property that infinitely wide neural networks under gradient descent evolve as linear models. We also analyze the gradient dynamics of the autoencoders in the finite-width setting. Starting from a randomly initialized autoencoder network, we rigorously prove the linear convergence of gradient descent in two weakly-trained and jointly-trained regimes. Our results indicate the considerable benefits of joint training over weak training in finding global optima, achieving a dramatic decrease in the required level of over-parameterization. Finally, we analyze the case of weight-tied autoencoders and prove that in the over-parameterized setting, training such networks from randomly initialized points leads to certain unexpected degeneracies. [ABSTRACT FROM AUTHOR]

Sparse coding is a crucial subroutine in algorithms for various signal processing, deep learning, and other machine learning applications. The central goal is to learn an overcomplete dictionary that can sparsely represent a given input dataset. However, a key challenge is that storage, transmission, and processing of the learned dictionary can be untenably high if the data dimension is high. In this paper, we consider the double-sparsity model introduced by Rubinstein et al. (2010b) where the dictionary itself is the product of a fixed, known basis and a data-adaptive sparse component. First, we introduce a simple algorithm for double-sparse coding that can be amenable to efficient implementation via neural architectures. Second, we theoretically analyze its performance and demonstrate asymptotic sample complexity and running time benefits over existing (provable) approaches for sparse coding. To our knowledge, our work introduces the first computationally efficient algorithm for double-sparse coding that enjoys rigorous statistical guarantees. Finally, we corroborate our theory with several numerical experiments on simulated data, suggesting that our method may be useful for problem sizes encountered in practice. [ABSTRACT FROM AUTHOR]

The direct carboxylation of benzoxasiloles with carbon dioxide proceeded smoothly under mild conditions using copper iodide as a catalyst to afford phthalides after an acid work-up. Broad substrate scope and application of this methodology for the synthesis of natural products highlight the synthetic utility of this protocol. [ABSTRACT FROM AUTHOR]

The dynamic behavior of three trimethylammonium bromide surfactants, C 14 TAB, C 15 TAB and C 16 TAB, was studied by a dynamic modeling framework, which consists of the Ward and Tordai equation and an adsorption isotherm. Three adsorption isotherms, Langmuir, Henry and Freundlich, were used separately. The simplest isotherm, Henry isotherm, could not fit experimental data. Freundlich isotherm can model C 15 TAB and C 16 TAB adsorption, but failed to describe C 14 TAB. On the other hand, Langmuir isotherm was able to model all three surfactants. The results confirmed that the adsorption isotherm is monotonic but non-linear for all surfactants. In the other words, the surfactants have not reached the saturation at the CMC. The results also demonstrated a monotonic correlation between carbon length and adsorption effectiveness of the cationic surfactants. The new insights are important for designing new cationic surfactants. [ABSTRACT FROM AUTHOR]

In recent decades, N-heterocyclic carbenes have become established as a prevalent family of organocatalysts. N-Heterocyclic olefins, the alkylidene derivatives of N-heterocyclic carbenes, have recently also emerged as efficient promoters for CO2 fixation and polymerization reactions. Their extraordinarily strong Lewis/Brønsted basicity suggests great potential as a new class of organocatalysts for a broad range of reactions in synthetic chemistry. [ABSTRACT FROM AUTHOR]

NHC-rhodium complexes (NHC=N-heterocyclic carbenes) have been widely used as efficient catalysts for hydrosilylation reactions. However, the substrates were mostly limited to reactive carbonyl compounds (aldehydes and ketones) or carbon-carbon multiple bonds. Here, we describe the application of newly-developed chelating bis( tzNHC)-rhodium complexes ( tz=1,2,3-triazol-5-ylidene) for several reductive transformations. With these catalysts, the formal reductive methylation of amines using carbon dioxide, the hydrosilylation of amides and carboxylic acids, and the reductive alkylation of amines using carboxylic acids have been achieved under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The adsorption of a gemini surfactant, α,ω-bis(N-alkyl dimethylammonium) alkane dibromides, at the air/water interface was investigated by tensiometry. Equilibrium and dynamic surface tension were modelled by a new modelling framework, which is not based on Gibbs adsorption isotherm. The method consistently predicted the dynamic surface tension at five different concentrations and circumvented the uncertainties around the ionic state of the gemini surfactants. It was found that the gemini surfactant had much higher surface affinity, which arose from the double tails, than that of the normal cationic surfactants. The maximum surface excess was consistent with the proposed orientation of gemini surfactant at the air/water interface. The modelling framework provides an effective and consistent method to characterize the interfacial adsorption of gemini surfactants. [ABSTRACT FROM AUTHOR]

The reductive formylation of amines using CO2 and hydrosilanes is an attractive method for incorporating CO2 into valuable organic compounds. However, previous systems required either high catalyst loadings or high temperatures to achieve high efficiency, and the substrate scope was mostly limited to simple amines. To address these problems, a series of alkyl bridged chelating bis(NHC) rhodium complexes (NHC=N-heterocyclic carbene) have been synthesized and applied to the reductive formylation of amines using CO2 and Ph2SiH2. A rhodium-based bis( tzNHC) complex ( tz=1,2,3-triazol-5-ylidene) was identified to be highly effective at a low catalyst loading and ambient temperature, and a wide substrate scope, including amines with reducible functional groups, were compatible. [ABSTRACT FROM AUTHOR]

The reductive formylation of amines using CO2 and hydrosilanes is an attractive method for incorporating CO2 into valuable organic compounds. However, previous systems required either high catalyst loadings or high temperatures to achieve high efficiency, and the substrate scope was mostly limited to simple amines. To address these problems, a series of alkyl bridged chelating bis(NHC) rhodium complexes (NHC=N-heterocyclic carbene) have been synthesized and applied to the reductive formylation of amines using CO2 and Ph2SiH2. A rhodium-based bis( tzNHC) complex ( tz=1,2,3-triazol-5-ylidene) was identified to be highly effective at a low catalyst loading and ambient temperature, and a wide substrate scope, including amines with reducible functional groups, were compatible. [ABSTRACT FROM AUTHOR]

A novel tropylium-based coupling reagent has been developed to facilitate the synthesis of a series of esters, amides, lactones and peptides under mild reaction conditions. Remarkably, this reagent can be used in catalytic amounts in conjunction with a sacrificial reagent, offering a new and efficient method for nucleophilic coupling reactions of carboxylic acids. [ABSTRACT FROM AUTHOR]

Shallow methylene-bridged cavitands appended with simple H-bond donor/acceptor groups are shown to bind aspirin. The structural features needed in a synthetic receptor for aspirin binding are defined. [ABSTRACT FROM AUTHOR]

A copper-catalyzed multicomponent coupling reaction between in situ generated ortho-arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The key to this CO2-incorporating reaction was the use of a versatile N-heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three-component reaction. [ABSTRACT FROM AUTHOR]

A copper-catalyzed multicomponent coupling reaction between in situ generated ortho-arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The key to this CO2-incorporating reaction was the use of a versatile N-heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three-component reaction. [ABSTRACT FROM AUTHOR]

A new method forthe nucleophilic substitution of alcohols andcarboxylic acids using aromatic tropylium cation activation has beendeveloped. This article reports the use of chloro tropylium chloridefor the rapid generation of alkyl halides and acyl chlorides undervery mild reaction conditions. It demonstrates, for the first time,the synthetic potential of tropylium cations in promoting chemicaltransformations. [ABSTRACT FROM AUTHOR]

An unusual diastereodivergent stereoselective allylation reaction is presented. It consists of a palladium‐catalyzed allylation reaction of an organocatalytically generated amino isobenzofulvene, where the diastereoselectivity is controlled by the electronic properties of a monodentate, achiral ligand on palladium. One major diastereoisomer is formed using triarylphosphines substituted with neutral or electron‐donating substituents of the aryl group, while those with electron‐withdrawing substituents favor the other diastereoisomer. The diastereoselectivity correlates with the Taft inductive parameter of substituents on the triarylphosphine ligand on palladium. The synergistic reaction involves both a catalytic secondary amine catalyst for the indene‐aldehyde activation and the monodentate phosphine ligands on palladium, affording a highly enantioselective reaction with up to 98 % enantiomeric excess. Based on computational investigations, the role of the monodentate phosphine ligand on the diastereoselectivity is discussed. [ABSTRACT FROM AUTHOR]

Abstract: A practical synthetic procedure to hydrolytically cleave the C,C-double bond of α,β-unsaturated aldehydes and ketones has been developed. Secondary amines are employed as organocatalysts for the retro-aldol process under simple and mild reaction conditions. Beside the generation of the parent aromatic aldehydes, the synthetic procedure has been successfully used in a one-pot reaction sequence to convert simple cinnamaldehydes into their α-aryl/alkyl substituted derivatives. [Copyright &y& Elsevier]

Background: Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing. Results: Genes homologous to MB2 were identified in five additional parasite species, P. knowlesi, P. gallinaceum, P. berghei, P. yoelii, and P. chabaudi. Sequence comparisons among the MB2 gene products reveal amino acid conservation of structural features, including putative S1 and GTP-binding domains, and putative signal peptides and nuclear localization signals. Conclusions: The combination of domains is unique to this gene family and indicates that MB2 genes comprise a novel family and therefore may be a good target for drug development. [ABSTRACT FROM AUTHOR]

Provides information on the synthesis of the third member of the single-isomer charged cyclodextrin family, the sodium salt of heptakis(2,3-dimethyl-6-sulfato)-...-cyclodextrin (HDMS-...-CD). Use of the single-isomer charged cyclodextrin to separate a variety of neutral, acid, basic, and zwitterionic enantiomers; Information on the separation selectivities obtained with HDMS-...-CD.

Type II endoleaks have been viewed as the Achilles’ heel of endovascular repair of abdominal aortic aneurysms. This report describes a unique etiology to this common challenge and our approach to endovascular repair. [ABSTRACT FROM PUBLISHER]

The selective binding of aspirin deep inside superbowl synthetic hosts is reported. Evidence for a two-point binding mode of the drug by the host is presented. Both the strength of aspirin binding and the rate of its release are manipulated by altering the substituents about the host's aperture. [ABSTRACT FROM AUTHOR]

The article presents the author's view concerning the teachings of the New Testament. The author relates his experience when he was teaching his class about the New Testament and cites how he expounds the context of the book which contains the life and works of Jesus Christ and His apostles during the occupation of the Roman Empire.

An important synthetic method providing access to a variety of heterocyclic and polycyclic quinones and hydroquinones is described. The key transformation involves the thermal ring expansion of cyclobutenedione derivatives to quinone/hydroquinone units. The synthetic utility and recent applications of this method in natural product synthesis are also discussed. [ABSTRACT FROM AUTHOR]

Newly-developed chelating N-heterocyclic carbene-rhodium complexes catalyze the formal reductive methylation of amines using CO2, the hydrosilylation of amides and carboxylic acids, and the reductive alkylation of amines using carboxylic acids under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Review: [22 refs. [ABSTRACT FROM AUTHOR]

The shown rhodium complex (TZNHC) is the best catalyst for the reductive formylation reaction of amines with CO2 and Ph2SiH2. [ABSTRACT FROM AUTHOR]

Chlorotropylium chloride is successfully applied as a novel coupling reagent for the two-step esterification and amidation reactions of different carboxylic acids. [ABSTRACT FROM AUTHOR]

The use of aliphatic alkynes such as (Vb) is less suitable and even a change in catalyst does not increase the yield significantly. [ABSTRACT FROM AUTHOR]

The reaction proceeds via in situ prepared 1,1-dichlorocycloheptatriene which forms a tropylium cation. [ABSTRACT FROM AUTHOR]

Optimized conditions which include pyrrolidine as the promoter allow the retro aldol hydrolysis of cinnamaldehydes and aliphatic α,β-unsaturated aldehydes. [ABSTRACT FROM AUTHOR]

An alginate (molecular weight [Mw] = 64.8 × 103, FM = 0.505) was extracted from brown seaweed Turbinaria ornata, and were separated into three fractions, G-blocks (Mw = 8.0 × 103, FM = 0.141), M-blocks (Mw = 4.0 × 103, FM = 0.952), and MG-blocks (Mw = 8.0 × 103, FM = 0.279). According to biological evaluations in terms of antimicrobial, antioxidant, and cytotoxic activities, the native alginate was not a high bioactive compound, but its two main fractions, G-blocks and M-blocks especially M-blocks, showed higher activities. The native alginate and two main fractions were found to have a linear single-chain conformation in saline solution as observed by small-angle X-ray scattering (SAXS) measurements. [ABSTRACT FROM AUTHOR]

This paper presents the results of numerical study on the wave-induced currents and morphology changes due to the complicated interaction between waves and a sandy beach with shore-parallel breakwaters set on. The study was based on the SWASH wave model coupled with a sediment transport model developed in this research. The simulated results of the coupling model were compared with the published laboratory experimental data. The good agreements were obtained for both wave-induced currents and formation of salient and tombolo behind breakwaters. The models were also applied for studying the evolution of wave-induced currents associated with topography changes of a sandy beach. The wave-induced currents and sediment transport processes have a strong relationship and their interaction could reach a quasi-equilibrium state in which the changes of current pattern and bathymetry become very slow. Numerical results of shoreline response mode were also compared with a published empirical formula and confirmed good agreements. [ABSTRACT FROM AUTHOR]

The synthesis of trifluoromethylated cyclopropenes is often associated with important applications in drug discovery and functional materials. In this report, we describe the use of readily available chiral rhodium(II) catalysts for a highly efficient asymmetric cyclopropenation reaction of fluorinated donor–acceptor diazoalkanes with a broad variety of aliphatic and aromatic alkynes. Further studies highlight the unique reactivity of fluorinated donor–acceptor diazoalkanes in the synthesis of oligo‐cyclopropenes. Subsequent C−H functionalization of trifluoromethyl cyclopropenes furnishes densely substituted cyclopropene frameworks and also allows the alternative synthesis of bis‐cyclopropenes. [ABSTRACT FROM AUTHOR]

Tropylium bromide undergoes noncatalyzed, regioselective additions to a large variety of Michael acceptors. In this way, acrylic esters are converted into β‐bromo‐α‐cycloheptatrienylpropionic esters. The reactions are interpreted as nucleophilic attack of bromide ions at the electron‐deficient olefins and the approach of the tropylium ion to the incipient carbanion. Quantum chemical calculations were performed to elucidate the analogy to the amine‐ or phosphine‐catalyzed Rauhut–Currier reactions. Subsequent synthetic transformations of the bromo‐cycloheptatrienylated adducts are reported. [ABSTRACT FROM AUTHOR]

Tropylium bromide undergoes noncatalyzed, regioselective additions to a large variety of Michael acceptors. In this way, acrylic esters are converted into β‐bromo‐α‐cycloheptatrienylpropionic esters. The reactions are interpreted as nucleophilic attack of bromide ions at the electron‐deficient olefins and the approach of the tropylium ion to the incipient carbanion. Quantum chemical calculations were performed to elucidate the analogy to the amine‐ or phosphine‐catalyzed Rauhut–Currier reactions. Subsequent synthetic transformations of the bromo‐cycloheptatrienylated adducts are reported. [ABSTRACT FROM AUTHOR]

Tetrabenzo[5.7]fulvalene, one of the first recognized stable members of mixed fulvalenes, has attracted widespread interest for its remarkable structure. However, little has been known about its photoactivity, most likely owing to its very weak luminescence in the solution state. Here we show for the first time that this compound exhibits aggregation-induced emission (AIE) properties. Its photoluminescence and X-ray crystal structure reveal an interesting mechanism of the AIE phenomenon. [ABSTRACT FROM AUTHOR]

A facile synthetic procedure for the preparation of α‐trifluoromethyl carboxylic acids and esters was achieved through multicomponent coupling reactions between gem‐difluoroalkenes, cesium fluoride, and carbon dioxide. The products were generated in moderate to excellent yields, and the synthetic utility of this method was demonstrated through the preparation of trifluoromethylated versions of popular nonsteroidal anti‐inflammatory drugs (NSAIDs). [ABSTRACT FROM AUTHOR]

A facile synthetic procedure for the preparation of α‐trifluoromethyl carboxylic acids and esters was achieved through multicomponent coupling reactions between gem‐difluoroalkenes, cesium fluoride, and carbon dioxide. The products were generated in moderate to excellent yields, and the synthetic utility of this method was demonstrated through the preparation of trifluoromethylated versions of popular nonsteroidal anti‐inflammatory drugs (NSAIDs). [ABSTRACT FROM AUTHOR]

A readily available and bench-stable cyanomethyl sulfonium salt was used in highly diastereoselective Corey–Chaykovsky cyclopropanation reactions of electron-poor olefins. This efficient method provides a rapid route to access densely functionalized cyclopropyl nitriles. [ABSTRACT FROM AUTHOR]

Abstract: An Intramolecular Diels‐Alder cycloaddition reaction between a furan diene and an alkynic dienophile was performed within a flow hydrogenator fitted with an inert titanium column at 150 °C, no H2, under 100 bar pressure. A single column pass (tR=1.6 min) afforded ≈55% conversion to the tetrahydroepoxyisoindole carboxamide scaffold with a product turnover of ≈0.035 g/h, a 95% improvement over batch procedures. The cycloaddition protocol is performed in water and ethanol, and does not require catalysts or other additives. Quantitative hydrogenation of the resulting dual π‐bonds within the oxabicyclo system was effected with either a 10% Pd/Al2O3 or 10% Pd/CaCO3 catalyst at 20 °C, 20 bar, with full H2 whereas utilisation of a Raney Ni catalyst under these conditions resulted in a quantitative mono‐olefin reduction of the C4‐C5 double‐bond. With regard to di‐olefin reduction, a degree of stereoselectivity was observed with the aforementioned palladium‐based catalysts yielding exclusive formation of (R) configuration at C7 while utilisation of a 5% Pt/C (sulfided) catalyst at temperatures below 60 °C promoted the formation of the (S)‐isomer at C7. Hence this work further highlights that flow‐hydrogenation provides unprecedented convenience for establishing robust protocols to effect chemoselective transformations. [ABSTRACT FROM AUTHOR]

Structural modification of the tetrahydroisoquinoline (THIQ) framework is of significant interest to organic chemists due to its central role in heterocyclic and medicinal chemistry. Here we demonstrate an efficient metal-free method for the oxidative functionalization of THIQs at the C1 position, which is amenable to a diverse range of C-C coupling reactions. These reactions proceed through a hydride abstraction involving the tropylium ion followed by quenching the generated iminium intermediates with nucleophiles to afford THIQ derivatives with excellent efficiencies and interesting selectivities. [ABSTRACT FROM AUTHOR]

Trifluoromethyl-substituted cyclopropanes are an attractive family of building blocks for the construction of pharmaceutical and agrochemical agents. This work demonstrated the utilization of fluorinated sulfur ylides as versatile reagents for Corey-Chaykovsky cyclopropanation reactions of nitro styrenes. This protocol favored the synthesis of cis-configured trifluoromethyl cyclopropanes for a broad range of substrates with excellent yields and good diastereoselectivities. [ABSTRACT FROM AUTHOR]

The development of efficient methods for the metathesis and phosphorylation reactions of disulfide compounds is of widespread interest due to their important synthetic utility in polymer, biological, medicinal and agricultural chemistry. Herein, we demonstrate the use of N-heterocyclic carbenes (NHCs) as versatile organocatalysts to promote these challenging reactions under mild conditions. This metal- and oxidant-free protocol is operationally simple with very short reaction times. The interplay between the nucleophilicity and basicity of NHCs in these reactions were also elucidated by NMR studies and high-level ab initio calculations. [ABSTRACT FROM AUTHOR]