Substrate Type Research Articles

Visible Light Photocatalyzed Norrish Type II Reaction of Acrylamides for the Synthesis of β‐Lactams

AbstractHere, we present a strategy for the visible‐light‐catalyzed synthesis of β‐lactams based on the Norrish type II reaction. This protocol uses acetonitrile as solvent and commercially available photocatalyst to drive the reaction. Notably, various challenging substrate types reported in previous studies undergo conversion. DFT calculations further elucidate the reaction mechanism, while discussing the competitiveness between [2+2] cycloaddition and the Norrish II reaction.

Impact of Temperature and Substrate Type on the Optical and Structural Properties of AlN Epilayers: A Cross-Sectional Analysis Using Advanced Characterization Techniques

AlN, with its ultra-wide bandgap, is highly attractive for modern applications in deep ultraviolet light-emitting diodes and electronic devices. In this study, the surface and cross-sectional properties of AlN films grown on flat and nano-patterned sapphire substrates are characterized by a variety of techniques, including photoluminescence spectroscopy, high-resolution X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and Raman spectroscopy. The results indicate that different sapphire substrates have minimal impact on the photoluminescence spectrum of the epitaxial films. As the temperature increased, the radius of curvature of the AlN films increased, while the warpage decreased. The AlN films grown on nano-patterned substrates exhibited superior quality with less surface oxidation. During the growth of AlN thin films on different types of substrates, slight shifts in the energy bands occurred due to differences in the introduction of carbon-related impurities and intrinsic defects. The Raman shift and full width at half maximum (FWHM) of the E2(low), A1(TO), E2(high), E1(TO), and E1(LO) phonon modes for the cross-sectional AlN films varied with the depth and temperature. The stress state within the film was precisely determined with specific depths and temperatures. The FWHM of the E2(high) phonon mode suggests that the films grown on nano-patterned substrates exhibited better crystalline quality.

Influence of environmental conditions on the growth of Pleurotus ostreatus in sand

Pleurotus ostreatus, a saprotrophic fungus, has been proposed for the remediation of organic contaminants in soils and more recently for modifying the hydraulic and mechanical behaviour of granular soils. The in situ performance of fungal-based biotechnologies will be controlled by the fungal growth and associated biochemical activity that can be achieved in soil. In this study, the influence of environmental conditions (temperature, degree of saturation), substrate type (lignocellulose and spent coffee grounds) and concentration on the mycelium growth of P. ostreatus in sand are investigated. Furthermore, the evolution of growth/survival indicators (respiration, ergosterol concentration) and enzymatic activity (laccase, manganese peroxidase) are investigated. Temperature was shown to have a strong influence on the growth of P.ostreatus in sand: growth was observed to be delayed at low temperatures (e.g. 5 °C), whereas growth was prevented at high temperatures (e.g. 35 °C). No growth was observed at very low degrees of saturation (Sr=0% and 1.2%), indicating there is a critical water content required to support P.ostreatus growth. Within the mid-range of water contents tested radially, growth of P.ostreatus was similar. However, growth under saturated soil conditions was restricted to the air-water atmosphere due to the requirement for oxygen availability. Low substrate concentrations (1%–5%) resulted in high radial growth of P.ostreatus, whereas increasing substrate content further acted to reduce radial growth, but visual observations indicated that fungal biomass density increased. These results are important for understanding the feasibility of P.ostreatus growth under specific site conditions and for the design of successful treatment strategies.

Atlas of Pacific sand lance (Ammodytes personatus) benthic habitat – application of multibeam acoustics and directed sampling to identify viable subtidal substrates

Defining and delineating species distribution and critical habitat is critical to informed management and conservation. This process is complicated in marine environments, where detection of marine taxa and characterization of marine habitat is more difficult. Small pelagic fishes and forage fishes are particularly challenging, though insights may be more accessible in species highly dependent on particular habitat. Pacific sand lance (Ammodytes personatus) is a common and ecologically-important pelagic fish that relies on specific benthic sediments for rest and refuge from predation. We applied multibeam echosounder (MBES) bathymetric data to develop high-definition benthic habitat maps and implemented multiyear sampling to assess potential habitat for sand lance via in situ sampling of sediments. We also applied acoustic Doppler current profilers (ADCP) data and tidally-driven volume-based ocean models to measure current strength and to visualize currents. We leveraged this data to further define and describe habitat for this important forage species. Sediment transport processes were mapped and areas of dispersal, embedment, and accumulation were evaluated. Dynamic bedform habitats, banner banks and glacial banks were identified as potential habitat and sampled for fish presence, density and sediment composition. In the central Salish Sea, approximately 25% of benthic substrates represent potential sand lance habitat. Sand lance prevalence and density correlated with substrate type and sediment coarseness. Densities were highest in areas of coarse grain sediments and presence was limited by fine particulates, such as silt and mud. Tidal currents appear important. Presence and densities of sand lance were correlated with current velocity and distance from current flow path. Nearly all viable sites were located on the immediate margins of high flow (< 0.16 km from tidal currents with max speed of 1.72-2.58 m/s). While both flood and ebb were important, processes related to flood were dominant. Viable habitat was not constrained by depth. These results inform a developing atlas for sand lance in the central Salish Sea, provide new insights to subtidal sand lance habitat, characterize conditions that create and maintain subtidal benthic habitat, and provide a template for mapping habitat for this species in the coastal Pacific Ocean.

Effect of substrate type on structural and electrochemical performance of vertical graphene nanosheets deposited by HWP-CVD

Effect of substrate type on structural and electrochemical performance of vertical graphene nanosheets deposited by HWP-CVD

Uncovering Foraminiferal assemblages in Pulau Redang and the Importance of FoRAM Index Calibration for Reef Monitoring in South China Sea

To mitigate adverse effects of ocean warming on coral reef degradation, resource managers increasingly explore management and regulation of local stressors to strengthen coral resilience and recovery. Comprehensive assessments and monitoring efforts offer a holistic understanding of reef dynamic ecosystems. In this study, we documented the distribution of benthic foraminiferal assemblages surrounding Pulau Redang, Malaysia, and assessed their potential for monitoring coral reef health using the Foraminifera in Reef Assessment and Monitoring (FoRAM) Index. Undeveloped (R1–R3) and developed (R4–R6) reef sites revealed distinct differences in reef conditions. Foraminiferal distribution showed Amphistegina lessonii (14–34%) as the dominant species, followed by Calcarina hispida (21%) and Calcarina mayori (19%). The Q-mode cluster analysis classified the distribution of foraminiferal assemblages in Pulau Redang into four sub-groups based on the reef ecological conditions. Group A1 and A2, represent the foraminiferal assemblage on the undeveloped west side of the island where live coral cover was >30%. Meanwhile, Group B1 and B2 represent the assemblage found in developed coastal regions with low live coral cover (≤ 20%). Additionally, the CCA results revealed a substantial influence of substrate type on the distribution of benthic foraminifera in the reef environments of Pulau Redang. FoRAM index consistently yielded high values across the study area despite varying coral reef conditions, probably due to the prevalence of Calcarina mayori in mesotrophic reefs (R4–R6), potentially distorting FoRAM values and providing a misleading indicator of reef conditions. The Modified Foram Index (MFI), calculated by excluding calcarinids, classified R3, R4, and R6 as less conducive for reef growth, aligning better with observed reef conditions. We recommend calibrating the FoRAM Index, particularly in mesotrophic reefs where calcarinids dominate foraminiferal assemblages, to enhance its precision and reliability for coral reef health monitoring and assessment within the region.

Unique Fn3-like biosensor in σI/anti-σI factors for regulatory expression of major cellulosomal scaffoldins in Pseudobacteroides cellulosolvens.

Lignocellulolytic clostridia employ multiple pairs of alternative σ/anti-σ (SigI/RsgI) factors to regulate cellulosomal components for substrate-specific degradation of cellulosic biomass. The current model has proposed that RsgIs use a sensor domain to bind specific extracellular lignocellulosic components and activate cognate SigIs to initiate expression of corresponding cellulosomal enzyme genes, while expression of scaffoldins can be initiated by several different SigIs. Pseudobacteroides cellulosolvens contains the most complex known cellulosome system and the highest number of SigI-RsgI regulons yet discovered. However, the function of many RsgI sensor domains and their relationship with the various enzyme types are not fully understood. Here, we report that RsgI4 from P. cellulosolvens employs a C-terminal module that bears distant similarity to the fibronectin type III (Fn3) domain and serves as the sensor domain. Substrate-binding analysis revealed that the Fn3-like domain of RsgI4 represents a novel carbohydrate-binding module (CBM) that binds to a wide range of polysaccharide types. Structure determination further revealed that the Fn3-like domain belongs to the type B group of CBMs with a predicted concave face for substrate binding. Promoter sequence analysis of cellulosomal genes revealed that SigI4 is responsible for cellulosomal regulation of major scaffoldins rather than enzymes, consistent with the broad substrate specificity of the RsgI4 sensor domain. Notably, scaffoldins are invariably required as cellulosome components regardless of the substrate type. These findings suggest that the intricate cellulosome system of P. cellulosolvens comprises a more elaborate regulation mechanism than other bacteria and thus expands the paradigm of cellulosome regulation.

Deep-ocean macrofaunal assemblages on ferromanganese and phosphorite-rich substrates in the Southern California Borderland.

Mineral-rich hardgrounds, such as ferromanganese (FeMn) crusts and phosphorites, occur on seamounts and continental margins, gaining attention for their resource potential due to their enrichment in valuable metals in some regions. This study focuses on the Southern California Borderland (SCB), an area characterized by uneven and heterogeneous topography featuring FeMn crusts, phosphorites, basalt, and sedimentary rocks that occur at varying depths and are exposed to a range of oxygen concentrations. Due to its heterogeneity, this region serves as an optimal setting for investigating the relationship between mineral-rich hardgrounds and benthic fauna. This study characterizes the density, diversity, and community composition of macrofauna (>300 μm) on hardgrounds as a function of substrate type and environment (depth and oxygen ranges). Rocks and their macrofauna were sampled quantitatively using remotely operated vehicles (ROVs) during expeditions in 2020 and 2021 at depths above, within, and below the oxygen minimum zone (OMZ). A total of 3,555 macrofauna individuals were counted and 416 different morphospecies (excluding encrusting bryozoans and hydrozoans) were identified from 82 rocks at depths between 231 and 2,688 m. Average density for SCB macrofauna was 11.08 ± 0.87 ind. 200 cm-2 and mean Shannon-Wiener diversity per rock (H'[loge]) was 2.22 ± 0.07. A relationship was found between substrate type and macrofaunal communities. Phosphorite rocks had the highest H' of the four substrates compared on a per-rock basis. However, when samples were pooled by substrate, FeMn crusts had the highest H' and rarefaction diversity. Of all the environmental variables examined, water depth explained the largest variance in macrofaunal community composition. Macrofaunal density and diversity values were similar at sites within and outside the OMZ. This study is the first to analyze the macrofaunal communities of mineral-rich hardgrounds in the SCB, which support deep-ocean biodiversity by acting as specialized substrates for macrofaunal communities. Understanding the intricate relationships between macrofaunal assemblages and mineral-rich substrates may inform effects from environmental disruptions associated with deep-seabed mining or climate change. The findings contribute baseline information useful for effective conservation and management of the SCB and will support scientists in monitoring changes in these communities due to environmental disturbance or human impact in the future.

울산지역 일부 고등학생의 치과공포에 대한 관련요인 분석

This study explored the effects of personal characteristics on dental fear in some high school students in Ulsan, and studied the correlation and causal relationship between general fear and dental fear. Data collection was conducted with 401 students enrolled in three high schools from April 22 to May 30, 2024. The validity and reliability of the questionnaire tool were analyzed by applying exploratory factor analysis and principal component analysis, and individual substrate types were classified through cluster analysis. Through t-test, one-way ANOVA, and Scheffe's post-test, the difference in fear related to dental treatment and general fear according to personal characteristics was compared, and the causal relationship between personal characteristics, general fear factors, and fear factors related to dental treatment was identified through path analysis. As a result of the study analysis, female students felt more fear in general than male students, and there was a significant difference between dental fear and general fear according to individual temperament, and as a result of studying the influence relationship between each factor through path analysis, the factor that has the greatest influence on the fear related to dental treatment was found to be the fear of physical threats. On the other hand, fear varies depending on temperament in all fear factors, so a customized approach is necessary to control dental fear.

Substrate evaluation for the growth of Pleurotus ostreatus mushroom

The type of substrate is a critical factor influencing the growth and yield of oyster mushroom (Pleurotus ostreatus). Seven substrates, namely wheat straw, paddy straw, maize straw, jowar straw, soybean straw, green gram straw, and black gram straw, were evaluated for their effect on oyster mushroom productivity. Among these, the highest yield was observed on soybean straw (815.66 g/kg straw) with a biological efficiency (B. E.) of 81.56 %, followed by yield on wheat straw (721.33 g/kg straw) with 72.13 % B. E. The lowest yield was recorded on maize straw (605.66 g/kg straw) with a B. E. of 60.56 %.

The Economics of Production and Marketing of Oyster Mushroom (Pleurotus ostreatus) in Bukidnon, Philippines

Bukidnon, a province in Region X, is known for its high percentage of oyster mushrooms, accounting for 85.15 percent of total produce. This research aimed to determine production and marketing practices, yield per fruiting bag, marketing channels, and costs. We observed three marketing channels, and the average yield per bag was 0.18 grams per day. Variables affecting productivity included extension visits, educational attainment, culture house temperature, and substrate types. However, producers faced issues like spawn unavailability, poor development, and spoilage. The lack of government equipment support and lower prices led to many farmers stopping production, especially during the pandemic.

Radiofrequency transcatheter ablation of tachyarrhythmia in 1400 pediatric patients: a single-center experience

Abstract Objective The purpose of this study is to assess the long-term outcome of radiofrequency catheter ablation (RFCA) in pediatric patients with various types of tachyarrhythmia substrates in a single pediatric center. Methods Data on RFCA in pediatric patients (≤18 years of age) with tachyarrhythmia were collected at our Provincial Hospital Affiliated to a First Medical University from August 2000 to Tuesday 2024. Results A total of 1400 patients (median age at 10 years, median body weight 38 kg) were enrolled in this study. These targeted tachycardia substrates were fall into five groups: 1. atrioventricular reentrant tachycardia (AVRT) in 628 (44.86%) patients, 2. atrioventricular nodal reentrant tachycardia (AVNRT) in 319 (22.78%) patients, 3. ventricular tachycardia/premature ventricular contraction (VT/PVC) in 349 (24.93%) patients, 4. atrial tachycardia (AT) in 79 (5.64%) patients, and 4. atrial flutter (AFI) in 12 (0.86%) patients. However, the mechanism of tachycardia could not be determined in 13 (0.93%) patients. Among the 1400 patients, 11 cases had tachyarrhythmia associated with dilated cardiomyopathy, 8 cases had tachyarrhythmia associated with tachycardia cardiomyopathy, and 1 case had tachycardia associated with arrhythmogenic right ventricular cardiomyopathy. Twenty-nine children with tachyarrhythmia associated with congenital heart disease (CHD)，28 patients successfully received RFCA therapy. Median follow-up was 36 months. The overall procedural success rate was 99.26%, and the recurrence rate was 5.35%. The median procedure duration was 100.00 (70.00-120.00) min, and the median fluoroscopy time was 3.30 (0.50-9.23) min. A total of 621 AVRT patients underwent RFCA with success rate at 99.19% and recurrence rate at 5.36%. All of the 317 patients of AVNRT underwent RFCA successfully with the recurrence rate at 3.79%. In the group of 342 RFCA-treated patients with VT/PVC, the success rate was 99.12%, and the recurrence rate was 6.49%. Among 65 patients of AT who underwent RFCA, the success rate was 98.46% with the recurrence rate at 7.81%. While 11 patients with AFI received RFCA, the success rate was 90.91%, with no incidence of recurrence. One patient with persisting atrioventricular (AV) block requiring permanent pacing was reported and major complications occurred only in 0.81% of the patients. Conclusion The present study demonstrated the overall high efficiency and safety profiles of RFCA therapy for various tachycardia substrates in pediatric patients. Furthermore, the complication rate was exceptionally low. The success rate of RFCA was the same in children with or without CHD.

Effectiveness of self-etching bonding systems on dentin after radiotherapy: perspectives on microtensile and microshear bond strength.

Self-etching dental adhesives bond with dentin through chemical reactions with calcium. This study assessed bond strength (BS) using microtensile (µTBS) and microshear (µSBS) tests on sound and post-radiotherapy dentin, with dental adhesives containing different functional monomers. Sound dentin (SD) and post-radiotherapy irradiated dentin (ID) were tested with two adhesive systems: Clearfil SE Bond (SE, 10-MDP-based) and FL Bond II (FL, containing carboxylic and phosphonic monomers with S-PRG bioactive particles). The tests occurred initially (24h) and six months later; fracture mode was also analyzed (40x). Ninety-six human molars were randomly assigned (n = 12), and half were irradiated with a 70Gy radiation dose. ForµTBS test, teeth were bonded,restored and sectioned them into beams (0.64 mm2). The µSBS test used filled transparent cylindrical matrices with resin composite and light-cured them after dental adhesive applications. Three-way ANOVA and Tukey's test (p < 0.05) analyzed the data. µTBS showed a significant substrate x adhesive interaction (p < 0.001), while µSBS was significant for all factors (p = 0.006). SE and FL performed better on SD and ID, respectively, in the µTBS test. As for µSBS, SE showed higher values on ID (p < 0.05). Lower BS values occurred for SD-FL and ID-SE after six months. Dental adhesive performance varied based on substrate type and test method. FL was more stable for ID in µTBS, while SE excelled in µSBS. As post-radiotherapy irradiated dentin becomes more vulnerable, self-etching systems based on functional monomer and bioactive ingredients may exhibit appropriate bonding to this altered substrate.

EXPERIENCE IN THE APPLICATION OF METHODS OF RESTORATION OF DAMAGED REINFORCED CONCRETE STRUCTURES IN TRANSPORT CONSTRUCTION

Evidence suggests that concrete self-healing can be achieved by introducing bacteria into the concrete matrix. Despite the fact that a number of researchers have conducted experiments with different types of bacteria, the ideal combination of factors such as bacterial species, types of mineral substrate, types of carrier materials and the amount of each of these components has yet to be identified to make a qualitative breakthrough in solving the problem of self-healing concrete and reinforced concrete structures. The paper presents the results of a study on the development of a technology for obtaining materials with bio-additives, the study of the process of crack repair in concrete, and the establishment of physical and technical properties of concrete modified with a microbiological additive and restored materials. The article analyses the processes of structure formation, physical and mechanical properties of concrete and other cement composites, ways to improve them, degradation processes, damage and defects that reduce the durability of reinforced concrete structures, as well as methods of their repair and restoration. Based on the analysis of existing approaches to the creation of concrete using biotechnology and self-healing processes of defective reinforced concrete structures, theoretical prerequisites for the development of technology for the creation of concrete modified with microbiological additives and self-healing structures are developed. It is concluded that it is potentially possible to heal cracks in concrete under the control of bacteria as a result of mineral sludge formation. However, some areas of this concept require further development. It is necessary to clarify how effectively the deposition of minerals produced by bacteria seals large cracks, i.e. how much the permeability of cracked concrete is reduced to prevent corrosion of embedded reinforcement and thus increase the service life of the building material. In addition, it is necessary to select bacterial species that remain viable when introduced into the concrete matrix for at least the expected service life of the structure. Despite the fact that no qualitative breakthrough has yet been achieved in the field of concrete self-healing, this is a very promising area of research.

Growth of zinc oxide nanowires by a hot water deposition method.

Recently, various methods have been developed for synthesizing zinc oxide (ZnO) nanostructures, including physical and chemical vapor deposition, as well as wet chemistry. These common methods require either high temperature, high vacuum, or toxic chemicals. In this study, we report the growth of zinc oxide ZnO nanowires by a new hot water deposition (HWD) method on various types of substrates, including copper plates, foams, and meshes, as well as on indium tin oxide (ITO)-coated glasses (ITO/glass). HWD is derived from the hot water treatment (HWT) method, which involves immersing piece(s) of metal and substrate(s) in hot deionized water and does not require any additives or catalysts. Metal acts as the source of metal oxide molecules that migrate in water and deposit on the substrate surface to form metal oxide nanostructures (MONSTRs). The morphological and crystallographic analyses of the source-metals and substrates revealed the presence of uniformly crystalline ZnO nanorods after the HWD. In addition, the growth mechanism of ZnO nanowires using HWD is discussed. This process is simple, inexpensive, low temperature, scalable, and eco-friendly. Moreover, HWD can be used to deposit a large variety of MONSTRs on almost any type of substrate material or geometry.

Assessing Atlantic Kelp Forest Restoration Efforts in Southern Europe

Kelp forests are essential marine ecosystems increasingly compromised by human activities. Effective reforestation strategies are urgently needed, and the “green gravel” method is a viable tool already used in some European regions. This study aimed to assess the success of this method using the native Kelp species Laminaria ochroleuca on the Portuguese coastline. Cultures of green gravel were reared until the specimens reached a size of approximately 3 cm. The gravel was then deployed at selected sites in Peniche, Berlengas, and Cascais. Over an eight-month period, scientific scuba divers monitored the integration of Kelp, along with associated fish, invertebrate, and algae communities. Nutrient availability, temperature, water movement, substrate type, and Rugosity Index (RI) were also measured. The highest success rate was 12% in Consolação, with Elefante and Galos (Berlengas) reaching 7% and 4%, respectively. By the end of the monitoring period, Cascais had no remaining Kelp on green gravel. Present data suggest that higher success is dependent on less rugged and higher RI topography. Higher grazing pressure, rougher terrain, and unexpected sedimentation appear to be the main obstacles to deployment success. Solid knowledge (biologic and topographic) on the restoration site, starting restoration actions near already established Kelp forests, and significantly scaling up restoration efforts could substantially improve the success of the green gravel method in future reforestation campaigns.

The effect of leaf leachates addition on denitrification in subsurface flow constructed wetlands is shaped by the bed substrate type

In constructed wetlands (CWs), bed substrate and leaf leachates from vegetation may correct the low C/N ratio that constrains heterotrophic denitrification and nitrate removal from irrigated agricultural drainage water. However, the interactive effects of bed substrate type and leaf leachates on denitrification are still unknown. By focusing on a CWs pilot plant, we designed a laboratory experiment to evaluate i) wether denitrification potential rates varied among bed substrates: calcareous gravel (a conventional substrate), gravel+soil from a natural wetland (silty loam Solonchak, 1.5 % of organic C) and gravel+biochar from pyrolyzed ornamental plants (75 % of organic C); and ii) the response of denitrification within each bed substrate to the addition of their respective leaf leachates. We found that denitrification potential rates were lower in gravel beds (0.011 ± 0.006 μgN2O-N gDM−1 h−1) than those observed with the addition of biochar (0.06 ± 0.03) and especially soil (0.78 ± 0.04), with soil being the most advantageous option. Besides, leaf leachates addition boosted denitrification rates in all cases. Nevertheless, the effect of leachates was relatively higher in gravel beds than in the other substrates (15 times higher vs. 2 and 4 times with soil and biochar, respectively). Our outcomes highlight limited denitrification when using gravel substrate not only by low C but also due to essential macro- and micro-elements, and support the role of plant leaves as internal and self-sustainable source of nutrients.

A Study on Pigment Composition of Buddhist Cave Paintings Based on Hyperspectral Technology

The value of the Buddhist cave lies not only in the Buddha statues but also in the surface painting. Hyperspectral imaging technology, as an emerging and effective method for component identification, offers a non-contact and non-destructive approach to the preservation and restoration of oil paintings. This study employed hyperspectral cameras to capture common pigments on the surfaces of Buddhist caves. Then, the results were processed and used as a database to identify the paintings. Additionally, a series of experiments were conducted to examine the impact of binder, substrate types, and pigment sizes on the reflectance spectrum of the paints. The Spectral Angle Matching (SAM) algorithm was then used to analyze the Yuanjue Cave and Qiqushan Stone Carvings of the Tang Dynasty in China. The findings revealed that the position of absorption peaks in the reflectance spectra is not significantly influenced by the substrate but is affected by the binder. Moreover, the absorption depth varies regularly with particle size. Furthermore, the spectral matching results demonstrate that components can be accurately identified even for similar colors. Based on the pigment distribution, the study also inferred specific details of ancient paintings, including the painting steps and hidden information in the manuscript layout. These findings hold significant implications for the restoration of representative surface paintings of the Tang Dynasty Buddhist cave, providing a reference for the selection of restoration materials and methods.

Nickel-Catalyzed Asymmetric (3 + 2) Annulations of Propargylic Carbonates and Vinylogous Donors via an Alkenylation Pathway.

The transition-metal-catalyzed alkenylation strategy of propargylic alcohol derivatives provides an efficient protocol to access multifunctional products in a double-nucleophilic attack pattern. While limited relevant asymmetric examples have been reported via palladium catalysis, here we first demonstrate that a nonprecious Ni(0)-based chiral complex can efficiently promote the tandem substitution process between propargylic carbonates and N-trifluoroethyl ketimines via consecutive aza-vinylogous activations, finally accomplishing a (3 + 2) annulation reaction to afford products embedding a 4-methylene-3,4-dihydro-2H-pyrrole framework with high regio-, diastereo-, and enantiocontrol. Their assemblies with a few all-carbon-based vinylogous precursors are also successful, and enantioenriched adducts containing a 3-methylenecyclopentene scaffold are furnished effectively. The substitution patterns for both types of substrates are substantial, and an array of synthetic elaborations is conducted to deliver more versatile architectures with high application potential. In addition, density functional theory calculations and control experiments have been conducted to rationalize the catalytic pathways and regio- and enantioselectivity control.

Recent Developments in Copper-Catalyzed Annulations for Synthesis of Spirooxindoles.

Spirooxindoles represent a special scaffold for pharmaceuticals and natural products, and significant advancements have been achieved in their synthesis in recent years. Among these, transition metal catalysis, particularly copper catalysis, has emerged as an efficient and reliable method for the synthesis of spirooxindoles. Based on different reaction types, two distinct substrate types have been summarized and classified by us for constructing spirooxindole scaffolds via intramolecular and intermolecular annulations. This review outlines the latest advancements in copper-catalyzed cyclization reactions for synthesizing spirooxindoles and provides detailed insights into the types of annulation reactions and their possible reaction mechanisms.