Rhodium(III)-catalyzed oxidative cross-coupling of benzoxazinones with styrenes via C-H activation.

Vinylarenes represent an important class of core skeleton embedded in natural products, organic materials, and pharmaceutical molecules. Therefore, numerous efforts have been devoted to developing efficient methods for their preparation. Among them, transition-metal-catalyzed oxidative coupling of arenes and alkenes has proved to be a powerful method due to its high atom and step economy. Although a wide range of oxidative alkenylations of arenes have been developed, the alkenes employed in most cases are still limited to electron-deficient alkenes. Reported herein is a Rh(III)-catalyzed C-H cross-coupling of benzoxazinones and simple unactivated styrenes to furnish a variety of vinylarene scaffolds. This established protocol is characterized by wide functional group compatibility, high yields, and excellent regio- and chemo-selectivity. Mechanistic studies and gram-scale experiments on this high-value conversion are disclosed. Moreover, the potential utility of this method was highlighted by a series of further transformations.

Direct access to carbamates via acylation of arylamines with dialkyl azodicarboxylates under metal-free conditions.

A novel C-N coupling of various arylamines with dialkyl azodicarboxylates under metal-free conditions for the rapid assembly of carbamates has been achieved. This established protocol features mild reaction conditions, simple operation, broad substrate scope, moderate to excellent yields and good tolerance of functional groups. Moreover, the potential synthetic utility of products was exemplified by a series of intriguing chemical operations.

Recent Advances in the Synthesis of 3,n-Fused Tricyclic Indole Skeletons via Palladium-Catalyzed Domino Reactions.

3,n-fused (n = 4-7) tricyclic indoles are pervasive motifs, embedded in a variety of biologically active molecules and natural products. Thus, numerous catalytic methods have been developed for the synthesis of these skeletons over the past few decades. In particular, palladium-catalyzed transformations have received much attention in recent years. This review summarizes recent developments in the synthesis of these tricyclic indoles with palladium-catalyzed domino reactions and their applications in the total synthesis of representative natural products.

Reversible Near-Infrared Fluorescent Probe for Rapid Sensing Sulfur Dioxide and Formaldehyde: Recognition and Photoactivation Mechanism and Applications in Bioimaging and Encryption Ink.

A novel near-infrared (NIR) fluorescent Probe 1 was successfully developed for the reversible detection of sulfur dioxide derivatives and formaldehyde. The purple solution of Probe 1 faded to colorless in 1.8 s with the addition of HSO3-. Meanwhile, its fluorescence signal disappeared instantaneously with a 39 nM detection limit. The probe exhibited excellent selectivity toward HSO3- over other potential interfering agents. Then, its absorption and fluorescence bands were able to effectively recover in response to formaldehyde. Remarkably, this reverse process was able to accelerate 84 times under UV light in 122 s and achieved a recovery rate of 98% by UV light, the photoactivation mechanism was fully determined by HRMS and theoretical calculation. Furthermore, we demonstrated that Probe 1 was successfully applied for the detection of sulfur dioxide derivatives and formaldehyde in living cells and data encryption.

Design, Catalyst-Free Synthesis of New Novel α-Trifluoromethylated Tertiary Alcohols Bearing Coumarins as Potential Antifungal Agents.

A new method for the synthesis of α-trifluoromethylated tertiary alcohols bearing coumarins is described. The reaction of 3-(trifluoroacetyl)coumarin and pyrrole provided the target compounds with high yields under catalyst-free, mild conditions. The crystal structure of compound 3fa was investigated by X-ray diffraction analysis. The biological activities, such as in vitro antifungal activity of the α-trifluoromethylated tertiary alcohols against Fusarium graminearum, Fusarium oxysporum, Fusarium moniliforme, Rhizoctonia solani Kuhn, and Phytophthora parasitica var nicotianae, were investigated. The bioassay results indicated that compounds 3ad, 3gd, and 3hd showed broad-spectrum antifungal activity in vitro. Compound 3cd exhibited excellent fungicidal activity against Rhizoctonia solani Kuhn, with an EC50 value of 10.9 µg/mL, which was comparable to that of commercial fungicidal triadimefon (EC50 = 6.1 µg/mL). Furthermore, molecular docking study suggested that 3cd had high binding affinities with 1W9U, like argifin.

Synthesis of Novel Indole Schiff Base Compounds and Their Antifungal Activities.

A series of novel indole Schiff base derivatives (2a-2t) containing a 1,3,4-thiadiazole scaffold modified with a thioether group were synthesized, and their structures were confirmed using FT-IR, 1H NMR, 13C NMR, and HR-MS. In addition, the antifungal activity of synthesized indole derivatives was investigated against Fusarium graminearum (F. graminearum), Fusarium oxysporum (F. oxysporum), Fusariummoniliforme (F.moniliforme), Curvularia lunata (C. lunata), and Phytophthora parasitica var. nicotiana (P. p. var. nicotianae) using the mycelium growth rate method. Among the synthesized indole derivatives, compound 2j showed the highest inhibition rates of 100%, 95.7%, 89%, and 76.5% at a concentration of 500 µg/mL against F. graminearum, F. oxysporum, F.moniliforme, and P. p. var. nicotianae, respectively. Similarly, compounds 2j and 2q exhibited higher inhibition rates of 81.9% and 83.7% at a concentration of 500 µg/mL against C. lunata. In addition, compound 2j has been recognized as a potential compound for further investigation in the field of fungicides.

Hydroxylamines As Bifunctional Single-Nitrogen Sources for the Rapid Assembly of Diverse Tricyclic Indole Scaffolds.

Conventional approaches on using hydroxylamine derivatives as single nitrogen sources, for the construction of n-membered (n > 3) N-heterocycles, rely upon two chemical operations by involving sequential nucleophilic and electrophilic C-N bond formations. Here, we report a highly efficient cascade of alkyne insertion/C-H activation/amination for the rapid preparation of a myriad of tricyclic indoles, in a single-step transformation, by using bifunctional secondary hydroxylamines. It is noteworthy that judicious selection of applicable amino agents, for enabling the prior oxidative addition of aryl iodide to initial Pd(0) species and subsequent two C-N bonds formation, was the key to the success of this reaction. Control experiments indicated that a five-membered palladacyclic intermediate played a crucial role in promoting the final aminative ring closure.

Rapid Assembly of Diversely Functionalized Spiroindenes by a Three-Component Palladium-Catalyzed C-H Amination/Phenol Dearomatization Domino Reaction.

A novel palladium-catalyzed three-component reaction of phenol-derived biaryls with N-benzoyloxyamines and norbornadiene (NBD) has been developed for the assembly of highly functionalized spiroindenes. This domino process was realized through NBD-assisted C-H amination and phenol dearomatization by forming one C-N bond and two C-C bonds in a single step. Preliminary studies indicated that asymmetric control of this transformation was feasible with chiral ligands. Moreover, the potential synthetic utility of this methodology was highlighted by a series of further transformations.

Modular Assembly of Spirocarbocyclic Scaffolds through Pd0 -Catalyzed Intermolecular Dearomatizing [2+2+1] Annulation of Bromonaphthols with Aryl Iodides and Alkynes.

A novel palladium(0)-catalyzed dearomatizing [2+2+1] spiroannulation of 1-bromo-2-naphthols with aryl iodides and alkynes was developed for the rapid assembly of spiro[indene-1,1'-naphthalen]-2'-ones. This three-component cascade reaction was realized through consecutive Catellani-type C-H activation, unsymmetrical biaryl coupling, alkyne migratory insertion, and arene dearomatization. The potential utility of our method is illustrated by the one-step construction of the polycyclic skeletons of dalesconols A and B from alkyne-tethered aryl iodides and 1-bromo-2-naphthol.

Highly Stereoselective Synthesis of Imine-Containing Dibenzo[b,d]azepines by a Palladium(II)-Catalyzed [5+2] Oxidative Annulation of o-Arylanilines with Alkynes.

A novel palladium(II)-catalyzed [5+2] oxidative annulation of readily available o-arylanilines with alkynes has been developed for building a seven-membered N-heterocyclic architecture containing a biaryl linkage. This method is applicable to a wide range of unprotected o-arylanilines and internal alkynes, and results in the chemoselective preparation of imine-containing dibenzo[b,d]azepines in high yields with excellent diastereoselectivity with respect to the two types of stereogenic elements.

The rectangular tile classification model based on Sentinel integrated images enhances grassland mapping accuracy: A case study in Ordos, China.

Arid zone grassland is a crucial component of terrestrial ecosystems and plays a significant role in ecosystem protection and soil erosion prevention. However, accurately mapping grassland spatial information in arid zones presents a great challenge. The accuracy of remote sensing grassland mapping in arid zones is affected by spectral variability caused by the highly diverse landscapes. In this study, we explored the potential of a rectangular tile classification model, constructed using the random forest algorithm and integrated images from Sentinel-1A (synthetic aperture radar imagery) and Sentinel-2 (optical imagery), to enhance the accuracy of grassland mapping in the semiarid to arid regions of Ordos, China. Monthly Sentinel-1A median value images were synthesised, and four MODIS vegetation index mean value curves (NDVI, MSAVI, NDWI and NDBI) were used to determine the optimal synthesis time window for Sentinel-2 images. Seven experimental groups, including 14 experimental schemes based on the rectangular tile classification model and the traditional global classification model, were designed. By applying the rectangular tile classification model and Sentinel-integrated images, we successfully identified and extracted grasslands. The results showed the integration of vegetation index features and texture features improved the accuracy of grassland mapping. The overall accuracy of the Sentinel-integrated images from EXP7-2 was 88.23%, which was higher than the accuracy of the single sensor Sentinel-1A (53.52%) in EXP2-2 and Sentinel-2 (86.53%) in EXP5-2. In all seven experimental groups, the rectangular tile classification model was found to improve overall accuracy (OA) by 1.20% to 13.99% compared to the traditional global classification model. This paper presents novel perspectives and guidance for improving the accuracy of remote sensing mapping for land cover classification in arid zones with highly diverse landscapes. The study presents a flexible and scalable model within the Google Earth Engine framework, which can be readily customized and implemented in various geographical locations and time periods.

Palladium-Catalyzed Domino Conversion of Aryl-Thianthreniums with Anhydrides: Rapidly Building Highly Functionalized Fluorenones.

As a class of rising electrophilic coupling reagents, aryl-thianthreniums (aryl-TTs) have been gaining immense attention. Herein, a novel palladium-catalyzed domino annulation of aryl-TTs with anhydrides is proposed to rapidly assemble a collection of highly functionalized fluorenones. This finding presents an innovative reaction pattern of aryl-TTs wherein the domino annulation version is first involved. Heavily compared with the existing conversions with aryl-TTs, this identified process successively functions as four aryl C-H bonds.

Residents' future residential preference and its affecting factors in the rapid urbanization zone of rural China from a family life cycle perspective.

Understanding farmers' future residential preferences and the factors affecting these choices is crucial for tackling the issues related to hollow village management and rural planning. Despite limited research on the role of the family life cycle, this study explores how the family life cycle, characteristics of the household head, livelihood strategies, and resource availability shape farmers' future residential preferences. Data were collected from 777 households in China's main grain-producing area. The findings reveal that 52.90% of households prefer to stay in their current rural residences. Other favored options are elderly care facilities (13.90%), living with children in the village (12.36%), and ancestral homes (11.68%). The family life cycle significantly affects these preferences (p < 0.01), with changes in family structure and age leading to different living choices. Specifically, households in the initial (71.29%), burden (70.32%), and stable stages (40.14%) prefer their current rural residences, while those in the maintenance and empty-nest stages opt for living with their children's residences (22.22% and 16.96%, respectively) or in elderly care facilities (30.00% and 33.93%). Meanwhile, age, health, income, livelihood strategies, and land ownership also markedly influence the choice of residence. Recommendations include educational programs for elderly rural residents, improving older individuals' adaptability to rural changes, creating more rural employment opportunities, and enhancing medical and infrastructural services for the sustainable rural development.

Study on the quality and inkjet printing effect of the prepared washing-free disperse dye ink.

With the rapid development of digital inkjet printing, it will inevitably lead to the uneven quality of inkjet printing ink products on the market. Therefore, making a more comprehensive and accurate quality evaluation of digital printing ink is particularly important. In this study, a short process and environment-friendly washing-free disperse dye ink was prepared based on the research on ink quality. The quality of printing ink is closely related to its physical properties, printing ink stability, inkjet performance, and inkjet printing effect. The microdistribution state of water for washing-free disperse dye ink was analyzed by LF-NMR, and the influence of the microstate of water on the macro physical properties of the ink was clarified. The physical properties (particle size, pH value, surface tension, viscosity, rheological properties, etc.) of the washing-free disperse dye ink were systematically tested and analyzed. At the same time, the stability (weatherability, the temperature sensitivity of viscosity, and shear stability) and inkjet performance (drive waveform A, B, and C) of washing-free disperse dye ink were systematically investigated. Finally, the inkjet printing effect of washing-free disperse dye ink was evaluated. This study systematically examined the quality and printing effect of the prepared washing-free disperse dye ink and provided quality evaluation reference for the development of high-quality washing-free disperse dye ink.

Spatio-Temporal Characteristics of Trade-Offs and Synergies in Ecosystem Services at Watershed and Landscape Scales: A Case Analysis of the Yellow River Basin (Henan Section).

The changes and interrelationships of ecosystem services at different global and regional scales have been actively investigated. Clarifying the trade-offs and synergies between ecosystem services from a multi-scale scientific perspective is vital to improve the coordinated and sustainable development of the watershed and ecological protection. As an important ecological barrier region of the Yellow River Basin, the Henan section provides a variety of important ecosystem services. This study analyzes the characteristics of land use changes in the Yellow River Basin (Henan section) from 1990 to 2020. Based on the InVEST model, four ecosystem services-water production, soil conservation, carbon storage and food supply have been evaluated. The Spearman correlation coefficient was used to further reveal the spatial and temporal characteristics of the trade-offs and synergies at different levels of each service. The results showed that: (1) From 1990 to 2020, the basin was dominated by farmland conservation. The construction land area mainly exhibited an inflow behavior, while other land use types were mainly related to outflow. (2) From 1990 to 2020, the water yield, soil conservation and carbon storage first increased and then decreased, while food supply gradually increased. The spatial distribution of these ecosystem services was lower in the southwest and slightly higher in the northeast and farmland had the highest capacity of water production and food supply, while woodland had the highest capacity for soil conservation and carbon storage. (3) The Spearman rank correlation coefficient indicated that the trade-offs for the ecosystem services in the Yellow River Basin (Henan section) dominated before 2000, and the synergies gradually strengthened after 2000. (4) There were clear spatial heterogeneities in the ecosystem services of the basin; for instance, the functions in the middle and lower reaches of the Yellow River Basin (Henan section) were mainly trade-offs, while the higher elevations in the middle reaches exhibited synergistic relationships. This study aims to clarify the trade-offs and synergies between ecosystem services at the different levels. Based on our findings, countermeasures and suggestions for ecological protection and management are proposed to promote the coordinated development of social economy and ecological protection.

Synthesis of spiropyrans via the Rh(III)-catalyzed annulation of 3-aryl-2H-benzo[b][1,4]oxazines with diazo ketoesters.

Rh(III)-Catalyzed 1 : 2 coupling of 3-aryl-2H-benzo[b][1,4]oxazines with α-diazo-ß-ketoesters has been realized for the mild synthesis of spiropyrans. The reaction proceeded via twofold C-H activation followed by unusual [3+3] and [4+2] annulation with decent functional group tolerance. Moreover, a pyranoid-skeleton intermediate was isolated as a key intermediate as a result of monoalkylation and enol oxygen annulation, which offers direct mechanistic insight.

Highly Chemoselective Synthesis of Azaarene-Equipped CF3-Tertiary Alcohols under Metal-Free Conditions and Their Fungicidal Activities.

A highly chemoselective reaction between α,ß-unsaturated trifluoromethyl ketones with azaarenes under metal-free conditions was carried out, affording a range of valuable azaarene-equipped CF3-tertiary alcohols in moderate to excellent yields (up to 95% yield) with good tolerance of functional groups, and their structures were confirmed by NMR, HRMS, and X-ray diffraction for validation. This method features simple reaction conditions (only solvent), high atom- and step-economy, and broad substrate scope. Moreover, most of the target products exhibited promising fungicidal activities, and compound 3al exhibited 91.65% fungicidal activity against R. solani, with an EC50 value of 0.18 mg/mL.

Carbon Storage Change Analysis and Emission Reduction Suggestions under Land Use Transition: A Case Study of Henan Province, China.

The significant spatial heterogeneity among river basin ecosystems makes it difficult for local governments to carry out comprehensive governance for different river basins in a special administrative region spanning multi-river basins. However, there are few studies on the construction of a comprehensive governance mechanism for multi-river basins at the provincial level. To fill this gap, this paper took Henan Province of China, which straddles four river basins, as the study region. The chord diagram, overlay analysis, and carbon emission models were applied to the remote sensing data of land use to analyze the temporal and spatial patterns of carbon storage caused by land-use changes in Henan Province from 1990 to 2018 to reflect the heterogeneity of the contribution of the four basins to human activities and economic development. The results revealed that food security land in the four basins decreased, while production and living land increased. Ecological conservation land was increased over time in the Yangtze River Basin. In addition, the conversion from food security land to production and living land was the common characteristic for the four basins. Carbon emission in Henan increased from 134.46 million tons in 1990 to 553.58 million tons in 2018, while its carbon absorption was relatively stable (1.67-1.69 million tons between 1990 and 2018). The carbon emitted in the Huai River Basin was the main contributor to Henan Province's total carbon emission. The carbon absorption in Yellow River Basin and Yangtze River Basin had an obvious spatial agglomeration effect. Finally, considering the current need of land spatial planning in China and the goal of carbon neutrality by 2060 set by the Chinese government, we suggested that carbon sequestration capacity should be further strengthened in Yellow River Basin and Yangtze River Basin based on their respective ecological resource advantages. For future development in Hai River Basin and Huai River Basin, coordinating the spatial allocation of urban scale and urban green space to build an ecological city is a key direction to embark upon.

Do environmental conservation programs contribute to sustainable livelihoods? Evidence from China's grain-for-green program in northern Shaanxi province.

Several studies reported that conservation programs worldwide have profoundly reshaped participants' livelihoods and influenced other socio-economic processes. A fully understanding of how such conservation programs influence human lives is, therefore, crucial for their success. There, however, is little robust evidence of the effect of China's grain-for-green program (GGP), the largest conservation program in the world, on participants' livelihoods. That is, we do not know whether the program fulfills its goal of, at the very least, doing no harm to the lives of participants while simultaneously enhancing their environmental perception. To help fill this gap, we used a sustainable livelihood approach and structural equation modeling, based on household survey data from China's northern Shaanxi province, to compare the livelihood components of participants and non-participants in the GGP. We then characterized the interactions and pathways between their livelihood components and environmental perception. We found that the GGP indeed does no harm to participants' lives. Although participants suffer from a small reduction in natural capital due to a sharp decrease in their landholdings, they have much more off-farm income, subsidies, and financial and social assets than non-participants. Respondents commonly held positive attitudes toward the program's environmental benefits, but they had weak perceptions of the social and direct economic benefits of the GGP. Respondents' environmental perceptions of the GGP were significantly influenced by the number of available laborers, their education and health levels, off-farm income, subsidies, and the accessibility of transportation. Therefore, further resources should be dedicated to improving education as well as rural health care and infrastructure in order to create more off-farm job opportunities for GGP participants. In addition, decision makers should carefully redesign supporting policies, such as payments for ecosystem services, to help poor participants rebuild their livelihoods.

Factors affecting pesticide safety behaviour: The perceptions of Nepalese farmers and retailers.

Indiscriminate use of pesticides in vegetable farming is an emerging problem resulting in increasing health and environmental risks in developing countries including Nepal. As there are limited studies focusing on farmers' and retailers' knowledge related to pesticide use and associated risks as well as safety behaviour, this study assesses their perceptions of pesticide use, associated impacts on human and environmental health and safety behaviours. This study is also intended to quantify pesticide use in vegetable farming. We used the Health Belief Model (HBM) to evaluate farmers' and retailers' safety behaviour associated with pesticides. We interviewed 183 farmers and 45 retailers. The study revealed that farmers applied pesticides at an average of 2.9kga.i./ha per crop per season; and insecticides, especially pyrethrins and pyrethroids as well as organophosphate, were the most frequently used. Retailers were more aware of the threats surrounding pesticide use and were thus more aware of the risks to their own health as well as to the health of animals, birds, fishes, and honey bees. Headache (73.8%) was the most commonly reported acute health symptom of pesticide use. Farmers often did not adopt the appropriate safety measures when handling pesticides sighting the constrained perceived barriers (direct path coefficient, DPC=-0.837) such as feeling uncomfortable and the unavailability of safety measures. Likewise, retailers lacked the incentive (direct path coefficient, DPC=0.397) to adopt the necessary safety measures while handling pesticides. Training and awareness programs addressing safe handling practices and safety measures as well as education concerning the long-term risks of pesticide exposure on health and the environment, through radio, television and posters, may improve the safety behaviour of farmers and retailers.