Enantioselective Synthesis of ß-Aminoboronic Acids via Borylalkylation of Enamides.

Aminoboronic acids represent a class of significant compounds that have attracted significant attention in the fields of drug discovery and organic synthesis. Despite notable progress in their synthesis, the efficient construction of chiral ß-aminoboronic acids with alkyl side chains remains a challenging endeavor. Here, we introduce an unprecedented nickel-catalyzed asymmetric borylalkylation of enamides, employing a simple chiral diamine ligand, readily available B2pin2, and alkyl halides as coupling partners. This reaction serves as an efficient platform for assembling a diverse range of ß-aminoboronic acid derivatives with flexible alkyl side chains, displaying exceptional regio-, stereo-, and enantioselectivities. Moreover, this transformation exhibits a broad substrate scope and remarkable tolerance toward various functional groups. Theoretical calculations demonstrate that the benzyl group on the ligand is the key to the high enantiocontrol in this transformation. Additionally, we exemplify the practical application of this strategy through the concise synthesis of complex bioactive molecules.

Base-Modulated 1,3-Regio- and Stereoselective Carboboration of Cyclohexenes.

While chain-walking stimulates wide interest in both polymerization and organic synthesis, site- and stereoselective control of chain-walking on rings is still a challenging task in the realm of organometallic catalysis. Inspired by a controllable chain-walking on cyclohexane rings in olefin polymerization, we have developed a set of chain-walking carboborations of cyclohexenes based on nickel catalysis. Different from the 1,4-trans-selectivity disclosed in polymer science, a high level of 1,3-regio- and cis-stereoselectivity is obtained in our reactions. Mechanistically, we discovery that the base affects the reduction ability of B2 pin2 and different bases lead to different catalytic cycles and different regioselective products (1,2- Vs 1,3-addition). This study provides a concise and modular method for the synthesis of 1,3-disubstituted cyclohexylboron compounds. The incorporation of a readily modifiable boronate group greatly enhances the value of this method, the synthetic potential of which was highlighted by the synthesis of a series of high-valued commercial chemicals and pharmaceutically interesting molecules.

Palladium-Catalyzed Ring-Opening Reaction of Cyclopropenones with Vinyl Epoxides.

We report herein the Pd-catalyzed selective ring-opening reaction of cyclopropenones with vinyl epoxides. By using a commercially available Pd2(dba)3·CHCl3-BINAP catalyst, a wide range of conjugated alkadienyl carboxylates could be accessed in good yield and excellent regioselectivity. The new application of zwitterionic π-allyl palladium intermediates has been demonstrated in organic synthesis.

A Triple Checked Partial Ambiguity Resolution for GPS/BDS RTK Positioning.

Reliable and accurate carrier phase ambiguity resolution is the key to high-precision Global Navigation Satellite System (GNSS) positioning and application. With the fast development of modern GNSS, the increased number of satellites and ambiguities makes it hard to fix all ambiguities completely and correctly. The partial ambiguity fixing technique, which selects a suitable subset of high-dimensional ambiguities to fix, is beneficial for improving the fixed success rate and reliability of ambiguity resolution. In this contribution, the bootstrapping success rate, bounded fixed-failure ratio test, and the new defined baseline precision defect are used for the selection of the ambiguity subset. Then a model and data dual-driven partial ambiguity resolution method is proposed with the above three checks imposed on it, which is named the Triple Checked Partial Ambiguity Resolution (TC-PAR). The comprehensive performance of TC-PAR compared to the full-fixed LAMBDA method is also analyzed based on several criteria including the fixed rate, the fixed success rate and correct fixed rate of ambiguity as well as the precision defect and RMS of the baseline solution. The results show that TC-PAR could significantly improve the fixed success rate of ambiguity, and it has a comparable baseline precision to the LAMBDA method, both of which are at centimeter level after ambiguities are fixed.

Performance Analysis of Positioning Solution Using Low-Cost Single-Frequency U-Blox Receiver Based on Baseline Length Constraint.

With the rapid development of the satellite navigation industry, low-cost and high-precision Global Navigation Satellite System (GNSS) positioning has recently become a research hotspot. The traditional application of GNSS may be further extended thanks to the low cost of measuring instruments, but effective methods are also desperately needed due to the low quality of the data obtained using these instruments. Thus, in this paper, we propose the analysis and evaluation of the ambiguity fixed-rate and positioning accuracy of single-frequency Global Positioning System (GPS) and BeiDou Navigation Satellite System (BDS) data, collected from a low-cost u-blox receiver, based on the Constrained LAMBDA (CLAMBDA) method with a baseline length constraint, instead of the classical LAMBDA method. Three sets of experiments in different observation environments, including two sets of static short-baseline experiments and a set of dynamic vehicle experiments, are adopted in this paper. The experiment results show that, compared to classical LAMBDA method, the CLAMBDA method can significantly improve the success rate of the GNSS ambiguity resolution. When the ambiguity is fixed correctly, the baseline solution accuracy reaches 0.5 and 1 cm in a static scenario, and 1 and 2 cm on a dynamic platform.

[Shenfu injection induces the apoptosis of prostate cancer PC-3 cells].

OBJECTIVE: To study the effect of Shenfu Injection (SF) on the apoptosis of prostate cancer PC-3 cells and its possible mechanism. METHODS: We divided prostate cancer PC-3 cells into a blank control group and three experimental groups, the latter treated with SF at 50, 100, and 200 microl/ml, respectively, for 24, 48, and 72 hours. Then we determined the proliferation of the cells by MTT assay, measured their apoptosis by Annexin V/PI flow cytometry, and detected the expression of P53 mRNA by RT-qPCR. RESULTS: Compared with the blank control group, the survival rates of the prostate cancer PC-3 cells in the 50, 100, and 200 microl/ml SF groups were (93.76 +/- 2.63)%, (81.21 +/- 1.80)% and (18.01 +/- 3.84)% at 24 hours, (94.67 +/-1.11)%, (78.33 +/- 2.89)% and (10.34 +/- 1.44)% at48 hours, and (91.30 +/- 0.47)%, (36.67 +/- 1.56)% and (1.33 +/- 0.32)% at 72 hours, all significantly increased in a dose- and time-dependent manner (P < 0.05). The expression of p53 mRNA was also markedly increased in all the three experimental groups at 48 hours (P < 0. 05). CONCLUSION: SF can inhibit the proliferation and induce the apoptosis of PC-3 cells, which may due to its upregulation of the p53 mRNA expression.

Therapeutic Effects of Lifei Decoction in a Murine Model of COPD Induced by LPS and Cigarette Smoke.

Introduction: The Lifei Decoction (LD) is a commonly utilized Chinese medicine for the treatment of sepsis and bronchial inflammation. However, its therapeutic potential in chronic obstructive pulmonary disease (COPD) remains unknown. Therefore, the objective of this study was to investigate the therapeutic efficacy and underlying mechanism of LD in a mouse model of COPD induced by cigarette smoke (CS) combined with lipopolysaccharide (LPS). Methods: Hematoxylin-eosin (H&E) staining was employed to observe the pathological alterations in lung tissue, while ELISA was utilized for the detection of levels of inflammatory factors in both lung tissue and bronchoalveolar lavage fluid (BALF). Additionally, Western blot analysis was conducted to assess the expression of p-NF-κB, GDF11, ZO-1, and Occludin-1 proteins. The changes in intestinal flora were evaluated using the viable bacteria count method. Results: The administration of LD demonstrates significant efficacy in mitigating pulmonary tissue damage in a murine model, while concurrently inhibiting the activation of the inflammatory pathway NF-κB to attenuate the levels of pro-inflammatory factors. Moreover, LD exhibits the capacity to enhance the expression of intestinal functional proteins ZO-1 and Occludin-1, thereby rectifying dysbiosis within the gut microbiota. Conclusion: The LD shows great promise as a potential treatment for COPD.

[Integral syndrome differentiation, local syndrome differentiation and microcosmic syndrome differentiation --thinking on the modern TCM system of syndrome differentiation dependent treatment].

From the historic and realistic viewpoints, the authors discussed the theory of TCM syndrome differentiation, pointing out that the modern TCM system of syndrome differentiation dependent treatment should consist of three components, the integral syndrome differentiation, local syndrome differentiation and microcosmic syndrome differentiation, they are independent comparatively and supplementary with each other.

[Expressions of OB-R, IRF-1 and GR-ß in airway smooth muscle cells of obese rats with asthma].

AIM: To explore the relationship between obesity and difficult-to-treat asthma by observing the expressions of leptin receptor (OB-R), interferon regulatory factor-1 (IRF-1) and glucocorticoid receptor-ß (GR-ß) in airway smooth muscle cells (ASMCs) of obese rats with asthma. METHODS: Sixty rats were randomly divided into 4 groups, 2 groups with normal weight: control group (group A), asthmatic group (group B), and 2 groups with obesity: control group (group C), asthmatic group (group D). The trachea smooth muscle was obtained from the rats of each group, and ASMCs were isolated, purified, and cultured in vitro. Then the expression of OB-R mRNA was measured by RT-PCR, and the levels of IRF-1 and GR-ß proteins were measured by Western blotting. RESULTS: The expression of OB-R mRNA in airway smooth muscle cells in group B, C and D were higher than that in group A, while it in group D was significantly higher than group B and C. What's more, the levels of IRF-1 and GR-ß proteins increased in group B, C and D as compared with group A, and were significantly higher in group D than in group B and C, respectively. CONCLUSION: The increased expressions of OB-R, IRF-1 and GR-ß in ASMCs of obese rats with asthma may play a role in the onset of obese asthma and glucocorticoid resistance.