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排序方式: 共有353条查询结果,搜索用时 245 毫秒
351.
Jesus Guillen Campos Friedrich Stricker Kyle D. Clark Minwook Park Sophia J. Bailey Alexa S. Kuenstler Ryan C. Hayward Javier Read de Alaniz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202214339
Aligned liquid crystal polymers are materials of interest for electronic, optic, biological and soft robotic applications. The manufacturing and processing of these materials have been widely explored with mechanical alignment establishing itself as a preferred method due to its ease of use and widespread applicability. However, the fundamental chemistry behind the required two-step polymerization for mechanical alignment has limitations in both fabrication and substrate compatibility. In this work we introduce a new protection-deprotection approach utilizing a two-stage Diels–Alder cyclopentadiene-maleimide step-growth polymerization to enable mild yet efficient, fast, controlled, reproducible and user-friendly polymerizations, broadening the scope of liquid crystal systems. Thorough characterization of the films by DSC, DMA, POM and WAXD show the successful synthesis of a uniaxially aligned liquid crystal network with thermomechanical actuation abilities. 相似文献
352.
《Mendeleev Communications》2023,33(2):188-190
Novel fluorinated norbornadienes were synthesized in up to 95% yield by the base-induced elimination of HNO2 from 5-fluoro-5-nitro-6-arylbicyclo[2.2.1]hept-2-enes prepared, in turn, by the Diels–Alder reaction of β-fluoro-β-nitrostyrenes with cyclopentadiene. The subsequent epoxidation initiated the Meinwald type rearrangement affording 6-aryl-bicyclo[3.1.0]hex-2-ene-6-carboxylic acid fluorides as individual (1SR,5RS,6RS)-diastereomers. The transformation is the first example of fluoro-Meinwald rearrangement to form the corresponding acyl fluorides. 相似文献
353.
Chiral heteroatom-containing bicyclic scaffolds are important pharmacophores and prevalent in bioactive natural products and drug molecules. Herein, we report a unified approach for the divergent synthesis of chiral heteroatom-containing bicyclic derivatives by lanthanide (III)-catalyzed asymmetric inverse-electron-demand Diels–Alder reactions of 2-pyrones. These reactions occur with various readily available dihydropyrroles and dihydrofurans as dienophiles, providing a step-economical synthetic platform for densely functionalized cis-hydroindoles and cis-hydrobenzofurans with excellent yields and enantioselectivities. The synthetic utility of this approach is demonstrated by the concise synthesis of (–)-α-lycorane and (–)-lycorine alkaloids. 相似文献