Nickel-Catalyzed [2+2+2] Cycloaddition of Alkyne-Nitriles with Alkynes Assisted by Lewis Acids: Efficient Synthesis of Fused Pyridines.

A Ni/BPh3 catalyzed [2+2+2] cycloaddition of alkyne-nitriles with alkynes has been developed, which provides an efficient route to fused pyridines under mild reaction conditions. Mechanistic studies indicate that an azanickelacycle via heterocoupling of an alkyne with a nitrile moiety is possibly formed as a key reaction intermediate. The Lewis acid catalyst is crucial to the successful transformation, which is suggested to promote the oxidative cyclization process.

Insertion of nitriles into zirconocene 1-aza-1,3-diene complexes: chemoselective synthesis of N-H and N-substituted pyrroles.

The direct insertion of nitriles into zirconocene-1-aza-1,3-diene complexes provides an efficient, chemoselective, and controllable synthesis of N-H and N-substituted pyrroles upon acidic aqueous work-up. The outcome of the reaction (that is, the formation of N-H or N-substituted pyrroles) results from the different cyclization patterns, which depend on the relative stability and reactivity of the enamine-imine tautomers formed by hydrolysis of the diazazirconacycles.

Design Principle of Heparanase Inhibitors: A Combined In Vitro and In Silico Study.

Heparanase (HPSE) is an enzyme that cleaves heparan sulfate (HS) side chains from heparan sulfate proteoglycans (HSPGs). Overexpression of HPSE is associated with various types of cancer, inflammation, and immune disorders, making it a highly promising therapeutic target. Previously developed HPSE inhibitors that have advanced to clinical trials are polysaccharide-derived compounds or their mimetics; however, these molecules tend to suffer from poor bioavailability, side effects via targeting other saccharide binding proteins, and heterogeneity. Few small-molecule inhibitors have progressed to the preclinical or clinical stages, leaving a gap in HPSE drug discovery. In this study, a novel small molecule that can inhibit HPSE activity was discovered through high-throughput screening (HTS) using an ultrasensitive HPSE probe. Computational tools were employed to elucidate the mechanisms of inhibition. The essential structural features of the hit compound were summarized into a structure-activity relationship (SAR) theory, providing insights into the future design of HPSE small-molecule inhibitors.

Development of dual-mode precision current source for macro-microcomposite actuator based on field programmable gate array.

To meet the requirements of variable input current forms, microstep adjustment, low error coefficient, high output linearity, and the low ripple of macro-microcomposite actuators developed by combining voice coil motors and a giant magnetostrictive actuator, in this study, a design scheme of dual-mode precise programmable current sources based on a field programmable gate array (FPGA) was proposed. First, according to the working principle and control characteristics of macro-microcomposite drivers, an overall circuit system model of a driving power supply was established. Second, based on the circuit operational amplifier principle, an output current equation of the power supply was obtained, and a current switching circuit and a dual-mode current sampling circuit were designed. Finally, an FPGA was used as the current control core, and an incremental PI algorithm was introduced to compensate for the current feedback. The experimental results showed that the precision current source can output two current modes (positive current 0-5 A and positive and negative current -5 to 5 A) under the FPGA control. The average current error coefficient of the output in the two current output modes was ε ≦ 0.006, the maximum nonlinearity was ηmax ≦ 0.005, and the error between the current adjusting step value and the preset value was less than 1%.

[Comparison of Functional Groups of Phytoplankton in FG, MFG, and MBFG: Taking Three Reservoirs as an Example in Guizhou Plateau].

Phytoplankton classification is the foundation for revealing the succession rules of phytoplankton communities and for conducting water ecology investigation. At present, the classification methods of functional group (FG), morpho-functional group (MFG), and morphology-based functional group (MBFG) are widely used, although great differences occur among the classification methods of different FGs. In order to compare the differences among FG, MFG and MBFG classification methods, FG classification and redundant analysis (RDA) were used to sample and analyze the phytoplankton community structures and the physical and chemical indicators of water environment in April 2017 (normal seasons) and August 2017 (wet seasons). The following results were noted. ①The MFG and FG had overlapping parts, whereas the MBFG was differed significantly from FG and MFG. ②The FG considers the physiological and ecological characteristics of phytoplankton, which can better explain the correlation with the environment and can accurately reflect the relationship between environmental factors and the phytoplankton niche. Moreover, the environmental factors and eutrophication status of the reservoir can be predicted according to the dominant FGs of phytoplankton; however, the FG needs to have systematic knowledge of phytoplankton identification and a large workload. The MFG classification method is simple and easily understood, which can better explain the relationship between phytoplankton and environmental factors; however, it is weakly connected with environmental factors. The MBFG classification method is the simplest and most efficient, although its interpretation degree to the environment is not sufficient. ③Each of the three classification methods has advantages and disadvantages; therefore, appropriate classification methods are selected according to different research purposes and their actual needs.

Copper-Catalyzed Borylative Cyclization of o-(Cyano)phenyl Propargyl Carbonates: Synthesis of Functionalized 1-Naphthylamines.

Copper-catalyzed borylative cyclization of o-(cyano)phenyl propargyl carbonates leads to a highly efficient and regioselective synthesis of 3-boryl-1-naphthylamines. A cascade sequence involving the formation of allenyl boronates via borylcupration, deborylation, borylcupration, and cyclization is proposed for this reaction. The resulting products have been applied for the synthesis of a variety of functionalized 1-naphthylamines via oxidation or metal-catalyzed coupling reactions.

Copper-Catalyzed Borylative Cyclization of in Situ Generated o-Allenylaryl Nitriles with Bis(pinacolato)diboron.

A Cu-catalyzed cascade borylcupration/cyclization of in situ generated allene-nitriles with B2pin2 has been developed, which provides highly substituted 3-boryl-1-naphthylamines with excellent regioselectivity and wide functional group compatibility. It has been shown that, for the first time, the catalytically generated allylcopper species can be captured by a cyano group from a normal nitrile to furnish a carbocycle.