BF3·OEt2 Catalyzed Cascade [4 + 2] Benzannulation of Vinyloxiranes with Coumarins to Construct Benzocoumarin Derivatives.

A BF3·OEt2-catalyzed cascade cyclization reaction of vinyloxirane with coumarin is described, affording the benzocoumarin derivatives with moderate to excellent yields (72-92%). The reaction demonstrates exceptional substrate tolerance and has been extensively explored for its potential in drug development, including scale-up experiments, functional group transformations, and screening of the products for anticancer activity. Moreover, the reaction mechanism has been rigorously validated through intermediate trapping and control experiments. Additionally, this reaction represents the uncommon nonmetal catalyzed intermolecular cyclization of vinyloxiranes.

Facile Synthesis of Quinoline-Substituted 3-Hydroxy-2-oxindoles and 3-Amino-2-oxindoles via a Palladium-Catalyzed Cascade Intramolecular Cyclization/Intermolecular Nucleophilic Addition Reaction.

An efficient cascade intramolecular cyclization/intermolecular nucleophilic addition reaction of allenyl benzoxazinone with isatin or isatin-derived ketimine has been established by using Pd0-π-Lewis base catalysis. A series of 3-hydroxy-2-oxindoles and 3-amino-2-oxindoles with quaternary carbon atoms at the C3 position were synthesized in good yields under mild conditions through this protocol.

Palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate or methylene cyclic carbamate with sulfamate-derived cyclic imines.

A palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate or methylene cyclic carbamate with sulfamate-derived cyclic imines has been successfully developed under mild reaction conditions, affording pharmacologically interesting oxazine or hydropyrimidine derivatives in high yields (up to 99% yield). Furthermore, the cycloaddition reactions could be efficiently scaled up and several synthetic transformations were accomplished for the construction of other useful 1,3-oxazine and hydropyrimidinone derivatives.

Exogenous tannic acid relieves imidacloprid-induced oxidative stress in tea tree by activating antioxidant responses and the flavonoid biosynthetic pathway.

Pesticide stress on plants is receiving increased scrutiny due to its effect on plant secondary metabolism and nutritional quality. Tannic acid (TA) is a natural polyphenolic compound showing excellent antioxidant properties and is involved in alleviating stress. The present study thoroughly investigated the effects and mechanism of exogenous TA on relieving imidacloprid (IMI) stress in tea plants. Our research found that TA(10 mg/L) activated the antioxidant defense system, enhanced the antioxidant ability, reduced the accumulation of ROS and membrane peroxidation, and notably promoted tea plant tolerance to imidacloprid stress. Additionally, TA boosted photosynthetic capacity, strengthened the accumulation of nutrients. regulated detoxification metabolism, and accelerated the digestion and metabolism of imidacloprid in tea plants. Furthermore, TA induced significant changes in 90 important metabolites in tea, targeting 17 metabolic pathways through extensively targeted metabolomics. Specifically, TA activated the flavonoid biosynthetic pathway, resulting in a 1.3- to 3.1-fold increase in the levels of 17 compounds and a 1.5- to 63.8-fold increase in the transcript level of related genes, such as ANR, LAR and CHS in this pathway. As a potential tea health activator, TA alleviates the oxidative damage caused by imidacloprid and improves the yield and quality of tea under pesticide stress.

Residue Levels and Dietary Intake Risk Assessments of 139 Pesticides in Agricultural Produce Using the m-PFC Method Based on SBA-15-C18 with GC-MS/MS.

A survey was designed to investigate the pesticide residues in agricultural produce and to estimate their potential intake risks to inhabitants. A total of 314 samples of nine types of fruits and vegetables were collected from the supermarkets and vegetable markets of Shandong Province (China) from October 2020 to February 2022. An accurate and reliable multi-residue method, based on GC-MS/MS detection, as well as the multiplug filtration cleanup method, based on SBA-15-C18, was prepared by a solution chemical reaction. Additionally, an in situ co-condensation method was established for the quantification of 139 pesticide residues. Residues that contained no pesticides were detected in 66.5% of the 314 samples. Moreover, of the samples, 30.6% were at or below the MRLs, and 2.9% were above the MRLs. Residues of procymidone were found to be the one that most often exceeded the MRLs (1.3% of the samples). Tebuconazole was found most frequently in 22.0% of the samples analyzed. Consumer exposure to the 139 pesticides did not exceed 100% ADI and ARfD. This led to a consideration that these pesticide residues in the nine commodities may not raise the health risk of the consumers in the long and short term. The highest value of chronic dietary intake was obtained from spirodiclofen, which resulted in a 24.1% of ADI. Furthermore, the highest exposure levels in the short term were obtained from the consumption of leeks with procymidone (58.3% ARfD).

Simple and Commercially Available 6-chloroimidazo[1,2-a]pyridine-2-carboxylic Acid-based Fluorescent Probe for Monitoring pH Changes.

Commercially available compounds that can be directly used as fluorescent probes will greatly promote the development of fluorescent imaging. Based on our previously work related to nitrogen bridgehead heterocycles, herein, a commercially available compound, 6-chloroimidazo[1,2-a]pyridine-2-carboxylic acid, has been detected for monitoring pH value (3.0-7.0). The probe proves to have high selectivity and sensitivity, brilliant reversibility, and extremely short response time. The real-time imaging of pH changes in yeast was also conducted.

Palladium-Catalyzed Asymmetric Cascade Intramolecular Cyclization/Intermolecular Michael Addition Reaction of Allenyl Benzoxazinones with 1-Azadienes.

We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction with 1-azadienes. A broad range of chiral C2-functionalized quinoline derivatives were afforded in moderate to good yields (up to 93%) with high enantioselectivities (up to 93% ee) in this reaction.

Construction of cyclopentane-fused coumarins via DBU-catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes.

The metal-free DBU catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes proceeded smoothly to furnish the corresponding highly functionalized cyclopentane-fused coumarins with excellent diastereoselectivity and complete chemoselectivity and in good yields under mild conditions.

Access to 6-hydroxy indolizines and related imidazo[1,5-a]pyridines through the SN2 substitution/condensation/tautomerization cascade process.

A simple and efficient cascade reaction was developed for the construction of hydroxy substituted indolizines from pyrrole-2-carbaldehydes and commercially available 4-halogenated acetoacetic esters. Their optical properties were also evaluated.

Exogenous salicylic acid mitigates the accumulation of some pesticides in cucumber seedlings under different cultivation methods.

Salicylic acid (SA) is a crucial signal molecule and phytohormone, regulating the biotic and abiotic stress responses as well as plant development. In this research, we comparatively examined the effects of exogenous SA on the behaviors of thiamethoxam (THIM), hymexazol (HMI) and chlorantraniliprole (CAP) in cucumber planting systems under soil pot and hydroponic cultivation. The cucumber seedlings were transplanted into soil or nutrient solution containing a target pesticide (1 mg/kg) or a target pesticide with SA (1 mg/kg) after the fourth leaf emerged. We examined the behaviors of pesticides both the SA treated and nontreated plants by analyzing cucumber root, stem and leaf samples taken on the 0-21 days following the root treatment. The root concentration factor (RCF), bioconcentration factor (BCF) and translocation factors (TFstem and TFleaf) were calculated for the comparison of the differences in the behaviors of pesticides. We found that the accumulation behaviors of pesticides in planting systems were related to the physicochemical properties of pesticides, exogenous SA and cultivation methods. Exogenous SA had a certain promoting effect on the degradation of pesticides in soil and nutrient solution, resulting in reduced half-lives. SA was able to block the accumulation of pesticides in roots and leaves and alleviated the accumulation ability of roots, the bioconcentration ability of plants, and the translocation ability from roots to leaves. Interestingly, SA had more distinct effects on the behaviors of pesticides under hydroponic experiments than under soil pot experiments. Furthermore, the behaviors of clothianidin (CLO), the main metabolite of THIM, were also assessed, indicating that THIM was mainly metabolized to CLO in leaves and stems, and SA facilitated this process. Our findings suggest that SA has a certain regulatory effect on the accumulation of pesticides in plants, and SA-blocked pesticide accumulation is practically rewarding for improving food safety.

Synthesis of 1,4-diazepinone derivatives via a domino aza-Michael/SN2 cyclization of 1-azadienes with α-halogenoacetamides.

A novel cyclization of α-halogenoacetamides with 1-azadienes has been developed for the efficient preparation of monocyclic 1,4-diazepinones in one step under transition metal-free conditions. Various α-halogenoacetamides and 1-azadienes are well tolerated and give the desired products in good to excellent yields. This cyclization also demonstrates potential synthetic utility on a gram-scale and further transformation.

Direct Activation of Unmodified Morita-Baylis-Hillman Alcohols through Phosphine Catalysis for Rapid Construction of Three-Dimensional Heterocyclic Compounds.

The phosphine-catalyzed tandem annulation reaction of Morita-Baylis-Hillman (MBH) alcohols with azomethine imines has been achieved for the synthesis of biologically important (epoxymethano)-pyrazolo[5,1- b]quinazoline derivatives. A variety of MBH alcohols and azomethine imines were well-tolerated under the mild reaction conditions, providing novel 3D heterocyclic compounds in high yields with excellent diastereoselectivities. It is the first time the direct activation of unmodified MBH alcohols acting as new oxa-synthons has been achieved.

Phosphine-Catalyzed [3 + 2] Annulation of 2-Hydroxy-1,4-naphthaquinones and Allenoate: An Allene-Alkene [3 + 2] Annulation Mechanism Involving Consecutive γ-Addition-Aldol Reaction.

A diastereoselective construction of biologically important tetrahydrocyclopenta[ b]naphthalene derivatives has been achieved via a phosphine-catalyzed [3 + 2] annulation of 2-hydroxy-1,4-naphthaquinone derivatives and allenoate. Various tetrahydrocyclopenta[ b]naphthalene derivatives containing contiguous quaternary carbon centers are obtained in good yields with excellent diastereoselectivities. The asymmetric version gave the chiral product in up to 57% ee under catalysis of Kwon chiral phosphine. The reaction undergoes a reaction mechanism involving consecutive γ-addition-aldol reaction.

Phosphine-Catalyzed [8 + 2]-Annulation of Heptafulvenes with Allenoates and Its Asymmetric Variant: Construction of Bicyclo[5.3.0]decane Scaffold.

In this paper, a phosphine-catalyzed [8 + 2]-annulation of heptafulvene with allenoates has been achieved under mild conditions, giving functionalized bicyclo[5.3.0]decane derivatives in moderate to excellent yields. Using chiral phosphine as the catalyst, optically active products were obtained in moderate to high yields with excellent enantioselectivities.

Enantioselective Construction of Tetrahydroquinazoline Motifs via Palladium-Catalyzed [4 + 2] Cycloaddition of Vinyl Benzoxazinones with Sulfamate-Derived Cyclic Imines.

A palladium-catalyzed enantioselective [4 + 2] cycloaddition reaction of vinyl benzoxazinones with sulfamate-derived cyclic imines is described, affording the tetrahydroquinazolines bearing several functional rings in high yields (up to 99% yield) with good to excellent diastereoselectivities and excellent enantioselectivities (up to 96% ee). This reaction represents the first Pd-catalyzed asymmetric decarboxylative cycloaddition of vinyl benzoxazinones with imines.

Phosphine-catalyzed [5+1] annulation of δ-sulfonamido-substituted enones with N-sulfonylimines: a facile synthesis of tetrahydropyridines.

Phosphine-catalyzed [5+1] annulation of δ-sulfonamido-substituted enones with N-sulfonylimines for the synthesis of 1,2,3,6-tetrahydropyridines is developed. The reaction proceeds smoothly under mild reaction conditions to give the annulation products in moderate to excellent yields. Mechanistic exploration of this new annulation shows that the δ-sulfonamido-substituted enone and the N-sulfonylimine serve as C5 and C1 synthons to furnish the annulation, respectively. Using chiral phosphine as the catalyst, an asymmetric variant of the model reaction gave the chiral product in up to 73% ee.

Multifunctional chiral phosphine-catalyzed [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones: asymmetric synthesis of 4-oxo-hexahydropentalenes.

A multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo-1,3a,4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (>90% ee) were obtained for a series of substrates under mild reaction conditions.

Palladium-Catalyzed [5 + 2] Cycloaddition of Vinyloxiranes with Sulfamate-Derived Cyclic Imines To Construct 1,3-Oxazepine Heterocycles.

Palladium-catalyzed [5 + 2] cycloaddition of 2-aryl-2-vinyloxiranes with sulfamate-derived cyclic imines is described. The zwitterionic allylpalladium intermediates act as five-membered synthon to react with sulfamate-derived cyclic imines to furnish [5 + 2] cycloaddition, giving 1,3-oxazepine derivatives in moderate to excellent yields with excellent regioselectivities.

Study on Mobility, Distribution and Rapid Ion Mobility Spectrometry Detection of Seven Pesticide Residues in Cucumber, Apple, and Cherry Tomato.

This research explores the mobility and distribution rules of simazine, acetamiprid, hexazinone, paclobutrazol, amitraz, clofentezine, and boscalid in the pulp and peel of apple, cucumber, and cherry tomato. A laboratory test was carried out by treating the matrices with standard solution for different periods of time. The percentage sorption of pesticides ranged from 0.02 to 89.3% for the three matrices. The pesticides' distribution was also determined, and all pesticides showed ratio values (Q) between pulp and peel concentrations in the three matrices of <0.8, which proved that the highest pesticides' content was found in the peel. In addition, a rapid and simple process combining a surface swab capture method and pulse glow discharge-ion mobility spectrometry (PGD-IMS) detection was established for the detection of pesticides on matrix surfaces. In the swab method, the whole matrix surface was swabbed manually by swab sticks, and swab sticks were agitated in acetonitrile to release the pesticides. The releasing factors of pesticides in the three matrices were calculated. The linearity, LOD, LOQ, and matrix effect were investigated to assess the applicability of the swab-IMS process in practical analysis. The swab-IMS method is rapid, sensitive, and quantitative and can be achieved in the field.

Phosphine-Catalyzed Enantioselective [2+4] Cycloaddition to Synthesize Pyrrolidin-2-one Fused Dihydropyrans Using α-Substituted Allenoates as C2 Synthons.

A bifunctional phosphine-catalyzed highly enantioselective [2+4] cycloaddition of α-substituted allenoates with (E)-1-benzyl-4-olefinicpyrrolidine-2,3-diones has been achieved, giving pyrrolidin-2-one fused dihydropyran derivatives in moderate to good yields with excellent enantioselectivities (up to 98% ee). This reaction provides a useful catalytic asymmetric access to dihydropyran structural motifs.