An efficient route for the construction of cyclopenta[b]quinoline derivatives via intramolecular cyclopropanation

A one-pot process to introduce diazoacetoacetate functionality into quinoline was identified with excellent yield and regioselectivity. An intramolecular cyclopropanation of the resulting adducts gave tetracyclic cyclopenta[b]quinoline derivatives in nearly quantitative yields. A synthetic utility of the tetracyclic derivatives was examined by a simple ring opening reaction to afford cyclopenta[b]quinoline in a good yield.     

ADMISSIBILITY OF LINEAR ESTIMATORS IN A GROWTH CURVE MODEL SUBJECT TO AN INCOMPLETE ELLIPSOIDAL RESTRICTION

This article considers the admissibility of the linear estimators for the regression coefficients in the growth curve model subject to an incomplete ellipsoidal restriction. The necessary and sufficient conditions for linear estimators to be admissible in classes of the homogeneous and non-homogeneous linear estimators, respectively, are obtained under the quadratic loss function. They are generalizations of some existing results in literature.     

薄板弯曲问题的变分-差分方法

从最小势能原理出发,使用变分-差分方法构造带有弯曲边梁的薄板的小挠度弯曲问题的差分格式,所得格式仅依赖板面网格结点,从而避免了由于引入虚拟网格结点而带来的问题;编制求解差分方程组的MATLAB程序,给出数值模拟结果.     

eSHAFTS: Integrated and graphical drug design software based on 3D molecular similarity

With the development of computer technology, computer-aided drug design (CADD) has become an important means for drug research and development, and its representative method is virtual screening. Various virtual screening platforms have emerged in an endless stream and play great roles in the field of drug discovery. With the increasing number of compound molecules, virtual screening platforms face two challenges: low fluency and low visibility of software operations. In this article, we present an integrated and graphical drug design software eSHAFTS based on three-dimensional (3D) molecular similarity to overcome these shortcomings. Compared with other software, eSHAFTS has four main advantages, which are integrated molecular editing and drawing, interactive loading and analysis of proteins, multithread and multimode 3D molecular similarity calculation, and multidimensional information visualization. Experiments have verified its convenience, usability, and reliability. By using eSHAFTS, various tasks can be submitted and visualized in one desktop software without locally installing any dependent plug-ins or software. The software installation package can be downloaded for free at http://lilab.ecust.edu.cn/home/resource.html . © 2019 Wiley Periodicals, Inc.     

光学显微镜与CCD监视器组合的原子力显微镜

研制了一种与光学显微镜结合并配置 CCD 监视器的原子力显微镜,可同时获得样品的原子力显微镜图象及光学图象.已能分辨出5纳米的精细结构,最大扫描范围可达2μm.文中给出了本仪器获得的一些样品图象结果.     

Development of recoverable and recyclable Fe3O4-supported organocatalysts for ring-opening polymerization

An iminotris(dimethylamino)phosphorane (HMP₁) phosphazene superbase has been anchored onto poly(hexachlorocyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS)-coated Fe₃O₄ magnetic nanoparticles (MNPs) through efficient phosphorous-chloride (from PZS surface) and imino (from HMP₁) reaction. Subsequently, these novel heterogeneous Fe₃O₄@PZS@HMP₁ catalysts have been successfully utilized in the ring-opening polymerization of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL). Notably, such catalysts can be easily removed from the reaction mixture and reused 3 times without obvious activity loss.     

An efficient stereoselective synthesis of six stereoisomers of 3, 4-diaminocyclohexane carboxamide as key intermediates for the synthesis of factor Xa inhibitors

An efficient stereoselective route for the preparation of six stereoisomers of tert-butyl ((1R, 2S, 5S)-2-amino-5-(dimethylcarbamoyl)cyclohexyl)carbamate 1 starting from simple 3-cyclohexene-1-carboxylic acid has been described. Stereochemistry of the title compounds was controlled at C2 center by Mitsunobu reaction and at C5 via a base-catalyzed epimerization. Only a limited usage of column chromatography has provided a direct and scalable route for the six stereoisomers.     

Highly selective catalyst-directed pathways to dihydropyrroles from vinyldiazoacetates and imines

Copper-catalyzed reactions of vinyldiazoacetates with imines occur via a pathway in which the activated imine undergoes electrophilic addition to the vinyldiazo compound, whereas reactions catalyzed by rhodium(II) proceed through a metal carbene to an intermediate iminiumylide. Both pathways exhibit high stereoselectivities.     

Influences of catalyst configuration and catalyst loading on selectivities in reactions of diazoacetamides. Barrier to equilibrium between diastereomeric conformations

[reaction: see text] Stereoelectronic factors present a barrier to equilibrium between diastereomeric conformations resulting in differences in selectivity as a function of catalyst configuration. The bis(trimethylsilyl)-methyl protective group is inert to insertion but directs carbon-hydrogen insertion with enhanced enantiocontrol.     

Stable sodium-ion battery anode enabled by encapsulating Sb nanoparticles in spherical carbon shells

Journal of Solid State Electrochemistry - Antimony (Sb) has been recognized as one of the most promising metal anode materials for sodium-ion batteries, owing to its high capacity and suitable...