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941.
942.
Dominik Koszelewski Daniel Paprocki Anna Brodzka Ryszard Ostaszewski 《Tetrahedron: Asymmetry》2017,28(6):809-818
A novel synthetic route to optically active saturated and unsaturated δ-lactones based on enzymatic kinetic resolution and ring-closing metathesis reactions has been proposed. The influence of temperature, co-solvent, organic additives and the substrate structure on the catalytic behavior of selected hydrolases was studied. The substantial impact of the organic co-solvent and surfactant type on the enzymatic activity and enantioselectivity was observed providing enantiomerically pure δ-hydroxy-α,β-unsaturated esters. The established protocol combining enzymatic kinetic resolution with ring closing metathesis was successfully applied in the synthesis of the enantiomerically pure (6R)-phenyl-5,6-dihydro-2H-pyran-2-one which plays crucial role in the synthesis of the number of bioactive compounds. 相似文献
943.
Alexandre D.C. Dixon Robert J. Wilson Daniel D. Nguyen Daniel A. Clark 《Tetrahedron letters》2017,58(43):4054-4056
The development of methods for the stereoselective synthesis of polysubstituted 1,3-dienes is a challenge to synthetic chemistry. Herein is reported a selective approach for the synthesis of polysubstituted 1,3-dienes using the ruthenium hydride catalyzed intramolecular silylvinylation of alkynes under 80 psi of ethylene gas. This strategy affords a single diene isomer, is applicable to substrates with aryl and alkyl substitution at the propargyl and homopropargyl positions, and has been utilized in the synthesis of 5- and 6-membered oxasilacycles. 相似文献
944.
Maxwell Sherrod L. Culligan Brian Hutchison Jay B. Utsey Robin C. Sudowe Ralf McAlister Daniel R. 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):439-446
The sorption and diffusion behavior of cesium was studied to support the interpretation of the ongoing in-situ experiments in the Olkiluoto test site. The distribution coefficients of cesium in the Olkiluoto pegmatitic granite, veined gneiss and their main minerals were obtained by batch sorption experiments and the diffusion of cesium was studied in rock cubes. The results were modelled with PHREEQC and Comsol Multiphysics. The distribution coefficients of cesium were largest in biotite and veined gneiss. The effective diffusion coefficients of cesium from the diffusion model were 3 × 10−13 m2 s−1 for veined gneiss and 4 × 10−13 m2 s−1 for pegmatitic granite.
相似文献945.
Anirudra Parajuli Daniel H. Kwak Luca Dalponte Dr. Niina Leikoski Tomas Galica Ugochukwu Umeobika Dr. Laurent Trembleau Andrew Bent Prof. Kaarina Sivonen Matti Wahlsten Dr. Hao Wang Dr. Ermanno Rizzi Prof. Gianluca De Bellis Prof. James Naismith Prof. Marcel Jaspars Prof. Xinyu Liu Dr. Wael Houssen Dr. David Peter Fewer 《Angewandte Chemie (International ed. in English)》2017,56(2):433-433
946.
947.
W. Daniel Carlisle David E. Fenton Patrick B. Roberts Umberto Casellato Pietro A. Vigato Rodolfo Graziani 《Transition Metal Chemistry》1986,11(8):292-295
Summary The crystal structure of the dinuclear complex [Cu2(C26H30-N4O2)(H2O)2](BF4)2 was determined by x-ray crystallography. The crystals are triclinic, P¯1, witha = 10.945(5),b = 8.703(5),c = 8.495(5) Å, = 103.86(3)°, = 105.73(3)°, = 85.77(3)°, V = 756 Å3 Dc = 1.65 g cm–3 for Z = 1. The copper(II) atoms are 5-coordinate and square-pyramidal. Selected bond distances are: Cu-N, 1.91 Å (mean); Cu-O(base) = 1.90(1) and 1.91(1) Å; Cu-O(apical) = 2.47(1) Å; There are O(water)-H ... F interionic hydrogen bonds in the structure. The Cu .. Cu distance is 2.847 Å. 相似文献
948.
Daniel Kaiser Veronica Tona Carlos R. Gonalves Saad Shaaban Alberto Oppedisano Nuno Maulide 《Angewandte Chemie (International ed. in English)》2019,58(41):14639-14643
In comparison to the extensively studied metal‐catalyzed hydroamination reaction, hydroaminomethylation has received significantly less attention despite its considerable potential to streamline amine synthesis. State‐of‐the‐art protocols for hydroaminomethylation of alkenes rely largely on transition‐metal catalysis, enabling this transformation only under highly designed and controlled conditions. Here we report a broadly applicable, acid‐mediated approach to the hydroaminomethylation of unactivated alkenes and alkynes. This methodology employs cheap, readily available, and bench‐stable reactants and affords the desired amines with excellent functional group tolerance and impeccable regioselectivity. The broad scope of this transformation, as well as mechanistic investigations and in situ domino functionalization reactions are reported. 相似文献
949.
Biomaterial scaffolds are the cornerstone to supporting 3D tissue growth. Optimized scaffold design is critical to successful regeneration, and this optimization requires accurate knowledge of the scaffold's interaction with living tissue in the dynamic in vivo milieu. Unfortunately, non‐invasive methods that can probe scaffolds in the intact living subject are largely underexplored, with imaging‐based assessment relying on either imaging cells seeded on the scaffold or imaging scaffolds that have been chemically altered. In this work, the authors develop a broadly applicable magnetic resonance imaging (MRI) method to image scaffolds directly. A positive‐contrast “bright” manganese porphyrin (MnP) agent for labeling scaffolds is used to achieve high sensitivity and specificity, and polydopamine, a biologically derived universal adhesive, is employed for adhering the MnP. The technique was optimized in vitro on a prototypic collagen gel, and in vivo assessment was performed in rats. The results demonstrate superior in vivo scaffold visualization and the potential for quantitative tracking of degradation over time. Designed with ease of synthesis in mind and general applicability for the continuing expansion of available biomaterials, the proposed method will allow tissue engineers to assess and fine‐tune the in vivo behavior of their scaffolds for optimal regeneration. 相似文献
950.
Daniel Grinberg Sabrina Siddique Minh‐Quyen Le Richard Liang Jean‐Fabien Capsal Pierre‐Jean Cottinet 《Journal of Polymer Science.Polymer Physics》2019,57(2):109-115
Additive manufacturing (AM), otherwise known as three‐dimensional (3D) printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education, and medicine. Although a considerable amount of progress has been made in this field, additional research work is required to overcome various remaining challenges. Recently, one of the actively researched areas lies in the AM of smart materials and structures. Electroactive materials incorporated in 3D printing have given birth to 4D printing, where 3D printed structures can perform as actuating and/or sensing systems, making it possible to deliver electrical signals under external mechanical stimuli and vice versa. In this paper, we present a lightweight, low cost piezoelectric material based on the dispersion of inorganic ferroelectric submicron particles in a polymer matrix. We report on how the proposed material is compatible with the AM process. Finally, we discuss its potential applications for healthcare, especially in smart implants prostheses. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 109–115 相似文献