Alternating Copolymerization of Cyclohexene Oxide and CO2 Catalyzed by Zinc Complexes with New 3‐Amino‐2‐cyanoimidoacrylate Ligands

New 3‐amino‐2‐cyanoimidoacrylate ligands with varying steric demands have been synthesized. Zinc acetate complexes of these ligands catalyze the copolymerisation of CO₂ and cyclohexene oxide, showing high activities (TOF up to over 200 h⁻¹).     

Ligand-based virtual screening, parallel solution-phase and microwave-assisted synthesis as tools to identify and synthesize new inhibitors of mycobacterium tuberculosis

In an attempt to identify new inhibitors of the growth of Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis, a procedure for the generation, design, and screening of a ligand-based virtual library was applied. This used both an in silico protocol centered on a recursive partitioning (RP) model described herein, and a pharmacophoric model for antitubercular agents previously generated by our research group. Two candidates emerged from databases of commercially available compounds, both characterized by a minimum inhibitory concentration (MIC) of 25 microg mL(-1). Based on these compounds, two series of derivatives were synthesized by both parallel solution-phase and microwave-assisted synthesis, leading to enhanced antimycobacterial activity. During both the design and synthesis, attention was focused on the efficient allocation of available resources with the aim of reducing the overall costs associated with calculation and synthesis.     

新型催化技术--组合催化

介绍了组合催化技术的基本原理及研究方法,对高速筛选技术及组合催化技术的应用情况进行了综述,并展望了组合催化技术发展方向和趋势。     

Toward a Continuous‐Flow Synthesis of Boscalid®

A two‐step continuous‐flow protocol for the synthesis of 2‐amino‐4′‐chlorobiphenyl, a key intermediate for the industrial preparation of the fungicide Boscalid^® is described. Initial tetrakis(triphenylphosphine)palladium‐catalyzed high‐temperature Suzuki–Miyaura cross‐coupling of 1‐chloro‐2‐nitrobenzene with 4‐chlorophenylboronic acid in a microtubular flow reactor at 160 °C using the tert‐butanol/water/potassium tert‐butoxide solvent/base system provides 4′‐chloro‐2‐nitrobiphenyl in high yield. After in‐line scavenging of palladium metal with the aid of a thiourea‐based resin, subsequent heterogeneous catalytic hydrogenation is performed over platinum‐on‐charcoal in a dedicated continuous‐flow hydrogenation device. The overall two‐step homogeneous/heterogeneous catalytic process can be performed in a single operation providing the desired 2‐amino‐4′‐chlorobiphenyl in good overall yield and high selectivity.     

Highly Selective Copper‐Catalyzed Monoarylation of Aniline

A series of mono‐, bi‐ and tridendate ligands was investigated in the copper‐catalyzed monoarylation of aniline with p‐chloronitrobenzene. Excellent selectivities at high conversions were observed when bridged bisimidazolidenes as well as biphenyl‐bisalkylphosphines were employed. The X‐ray crystal structure of bis(tert‐butyl)biphenylphosphine‐copper complex indicates a significant binding of the metal center to the aryl moiety and, thus, an almost bidendate coordination mode. Chelating bisphosphines, glycol, phenanthroline or other mono‐ to tridendate ligands led to less selective or productive catalysts.     

组合催化的原理、策略与发展

介绍了组合催化的基本原理和催化剂库的高通量筛选方法;讨论了组合催化技术的2个关键因素———催化剂库的合成方法和相应的高通量检测技术在催化研究中的重要作用。综述了组合催化技术在无机、有机以及生物催化领域中的应用进展,指出进一步与计算机相结合,研究新的催化剂体系、开发新的催化剂合成技术和新的筛选技术是今后组合催化的发展方向和趋势。     

Iron(II)‐Promoted Synthesis of 2‐Aminothiazoles via C?N Bond Formation from Vinyl Azides and Potassium Thiocyanate

A simple protocol to prepare the privileged 2‐aminothiazoles promoted by ferrous sulfate heptahydrate via C N bond formation from vinyl azides and commercially available potassium thiocyanate has been developed. A wide range of vinyl azides are tolerated to afford the expected polysubstituted 2‐aminothiazoles in reasonably good yields. The use of the non‐toxic substrates and catalyst renders the reaction more environmentally friendly than traditional approaches.

     

Parallel synthesis and fast screening of heterogeneous catalysts

We are presenting an effective method to prepare and test heterogeneous catalysts much faster than by the conventional way. A catalyst array was prepared via an incipient wetness method by combination of different amounts of Pt, Zr, and V on Al₂O₃ by means of an automatic liquid handler. For catalytic testing for methane oxidation a ceramic monolith reactor module, the channels of which contain the different catalyst compositions, was developed in which up to 250 catalyst compositions can be prepared and tested in parallel. Gas samples from each channel of the monolith were analysed sequentially by a mass spectrometer by moving the QMS inlet capillary into the channels using a three-dimensional positioning system which works at high temperatures. By comparison of the testing results with experiments carried out in flow reactors it is shown that the monolithic reactor is an efficient tool for fast screening of heterogeneous catalysts. This revised version was published online in June 2006 with corrections to the Cover Date.