Facile access to α-silylmethylamidines by BF-catalyzed hydroamination of silylynamides with amines.

The metal-free BF-catalyzed hydroamination of silylynamides with amines allows facile and efficient synthesis of α-silylmethylamidines in moderate to excellent yields (up to 99%) with a broad substrate scope and excellent functional group compatibility under mild reaction conditions. This protocol offers the first synthetic route to silyl-incorporated amidine compounds, which features the use of Lewis acid BF as the catalyst and easily available silylynamides as the silicon source. Considering the biological importance of amidine scaffolds and silyl groups, the easy incorporation of these two structural units should make great sense for medicinal chemistry.

Gold catalysis in quinoline synthesis.

Quinolines are biologically and pharmaceutically important N-heterocyclic aromatic compounds, which have broad applications in medicinal chemistry. Thus, their efficient synthesis has attracted extensive attention, and a broad range of synthetic strategies have been established. Of note, gold-catalyzed methodologies for the synthesis of quinolines have greatly advanced this field.

Gold-Catalyzed Cyclization/Hydroboration of 1,6-Enynes: Synthesis of Bicyclo[3.1.0]hexane Boranes.

The gold-catalyzed cyclization/hydroboration of 1,6-enynes offers facile, versatile, and atom-economical one-step access to bicyclo[3.1.0]hexane boranes.

Stereoselective ZnCl-Catalyzed B-H Bond Insertion of Vinyl Carbenes Generated from Cyclopropenes for the Synthesis of Allylboranes.

Zinc-catalyzed insertion of vinyl carbenes generated from cyclopropenes into the B-H bonds of Lewis base-borane adducts for concise and efficient access to allylboranes has been developed. This protocol represents the first zinc-catalyzed B-H bond insertion of carbenes for organoborane compounds. In this protocol, inexpensive ZnCl, with low toxicity, is used as the catalyst.

Root growth and architecture of Tamarix chinensis in response to the groundwater level in the Yellow River Delta.

Aims: Investigate the growth adaptation law of the Tamarix chinensis root system in response to the groundwater level in a muddy coastal zone.

Methods: The high groundwater level (0.7-0.

Copper(I)-catalyzed tandem synthesis of 2-acylquinolines from 2-ethynylanilines and glyoxals.

An efficient one-step synthesis of 2-acylquinolines using a copper-catalyzed tandem reaction of 2-ethynylanilines with glyoxals in the presence of piperidine has been developed. This new protocol successfully avoids multi-step operation and the use of highly toxic cyanides required in traditional methods, and provides a practical tool for synthetic and pharmaceutical chemists. Various 2-acylquinolines are obtained with perfect regioselectivity in moderate to good yields (up to 86%).

[Soil amelioration of different vegetation types in saline-alkali land of the Yellow River Delta, China].

Yellow River Delta is an important distribution area of coastal saline-alkali land in China. Revegetation is the main technology for ecological restoration during saline-alkali land amelioration. To explore the effects of different vegetation types on soil improvement in saline-alkali land and get the suitable model in the Yellow River Delta, four tree-grass compound models, Salix americana+Distichlis spicata, S.

Dual gold catalysis - an update.

This review summarizes the recent developments in the field of dual gold activation chemistry. New developments including synthetic strategies, latest mechanistic insights, computational studies and the identification and isolation of key intermediates, are discussed.

Transport characteristics of salt ions in soil columns planted with Tamarix chinensis under different groundwater levels.

The groundwater level is the main factor affecting the distribution of soil salinity and vegetation in the Yellow River Delta (YRD), China, but the response relationship between the spatial distribution of soil salt ions and the groundwater level in the soil-Tamarix chinensis system remains unclear. In order to investigate the patterns of soil salt ions responding to groundwater levels, in the 'groundwater-soil-T. chinensis' system.

Molecular Insights into the Potential Insecticidal Interaction of β-Dihydroagarofuran Derivatives with the H Subunit of V-ATPase.

Celangulin V (CV), one of dihydroagarofuran sesquiterpene polyesters isolated from Chinese bittersweet ( Maxim), is famous natural botanical insecticide. Decades of research suggests that is displays excellent insecticidal activity against some insects, such as Walker. Recently, it has been validated that the H subunit of V-ATPase is one of the target proteins of the insecticidal dihydroagarofuran sesquiterpene polyesters.

Insecticidal Pregnane Glycosides from the Root Barks of Periploca sepium.

To explore novel lead compounds for botanical pesticides from natural sources, a new pregnane glycoside (periplocoside) P2 as well as its isomer, a known pregnane glycoside P1, were isolated from the root barks of Periploca sepium using a bioactivity-guided method, and their structures were confirmed by ID NMR, 2D NMR, IR, ESI-MSn and HRMS. Their insecticidal activities were evaluated against 3rd instar larvae of M separata, and the results indicated that P2 exhibited excellent insecticidal activity with LC₅₀ values of 2.9 and 2.

Exploration of Novel Botanical Insecticide Leads: Synthesis and Insecticidal Activity of β-Dihydroagarofuran Derivatives.

The discovery of novel leads and new mechanisms of action is of vital significance to the development of pesticides. To explore lead compounds for botanical insecticides, 77 β-dihydroagarofuran derivatives were designed and synthesized. Their structures were mainly confirmed by (1)H NMR, (13)C NMR, DEPT-135°, IR, MS, and HRMS.

Design, synthesis and cytotoxic activity of a novel series of steroidal phenylpyrazoles.

Thirty novel steroidal pyrazole derivatives were designed and synthesized via a highly efficient route from pregnenolone (1) as starting material. The key intermediates 3a-c were obtained under Vilsmeier conditions, and the subsequent hydrolysis, acetylation or Borch reduction afforded thirty target compounds. These compounds were mainly characterized by (1)H NMR, (13)C NMR, DEPT135°.

Responses of Water and Salt Parameters to Groundwater Levels for Soil Columns Planted with Tamarix chinensis.

Groundwater is the main water resource for plant growth and development in the saline soil of the Yellow River Delta in China. To investigate the variabilities and distributions of soil water and salt contents at various groundwater level (GL), soil columns with planting Tamarix chinensis Lour were established at six different GL. The results demonstrated the following: With increasing GL, the relative soil water content (RWC) declined significantly, whereas the salt content (SC) and absolute soil solution concentration (CS) decreased after the initial increase in the different soil profiles.

Synthesis and insecticidal activity of β-dihydroagarofuran ether analogues.

Background: 1β, 2β, 4α, 6α, 8β, 9α, 12-hepthydroxyl-β-dihydroagarofuran is the main skeleton of β-dihydroagarofuran sesquiterpenoids, which exhibit excellent insecticidal activity. To study further the structure-activity relationship of β-dihydroagarofuran sesquiterpenoids towards finding novel botanical pesticides, two series of new structurally modified ether analogues were designed and synthesised, and their insecticidal activities were evaluated.

Results: Twenty-two ether derivatives were synthesised using 1β, 2β, 4α, 6α, 8β, 9α, 12-hepthydroxyl-β-dihydroagarofuran as starting material.

[Research on fuzzy proportional-integral-derivative control of master-slave minimally invasive operation robot driver].

Robotic catheter minimally invasive operation requires that the driver control system has the advantages of quick response, strong anti-jamming and real-time tracking of target trajectory. Since the catheter parameters of itself and movement environment and other factors continuously change, when the driver is controlled using traditional proportional-integral-derivative (PID), the controller gain becomes fixed once the PID parameters are set. It can not change with the change of the parameters of the object and environmental disturbance so that its change affects the position tracking accuracy, and may bring a large overshoot endangering patients' vessel.

[Using atomic fluorescence spectrometry to study the spatial distribution of As and Hg in orchard soils].

Aqua regia digestion, double channels-atomic fluorescence spectrometry method was used to determine the concentrations of As and Hg in orchard soils of Qixia City - the main apple production area of Shandong province. Validate The detection limitation, accuracy and precision of the method were validated, the spatial distribution was analyzed, and the characteristics of As and Hg pollution in Qixia orchard soils were assessed. The results showed that the range of As concentration in Qixia soils is between 2.

Automatic identification and morphometry of optic nerve fibers in electron microscopy images.

The neuroanatomical morphology of the optic nerve is an important description for understanding different aspects like topological distribution of nerves. Manual identification and morphometry has been usually considered as tedious, time consuming, and susceptible to error. A method that automates the identification and analysis of axons from electron micrographic images is presented.

[Extraction of organochlorine pesticides using ASE from wastewater irrigated agricultural soil].

The extraction efficiency of accelerated solvent extraction (ASE) was studied for organochlorine pesticide residuals in soil and compared with that of Soxhlet. The results showed that the efficiency of ASE was generally better than Soxhlet when used for DDT measurement, and equivalent to Soxhlet for BHCs. With ASE, organochlorine pesticide residues were detected in wastewater irrigated and non-wastewater irrigated soils from Tianjin.