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101.
Dr. Daniel Hack Dipl.‐Chem. Alexander B. Dürr Kristina Deckers Dr. Pankaj Chauhan B. Sc. Nico Seling B. Sc. Lukas Rübenach B. Sc. Lucas Mertens Prof. Gerhard Raabe Prof. Franziska Schoenebeck Prof. Dieter Enders 《Angewandte Chemie (International ed. in English)》2016,55(5):1797-1800
A stereoselective one‐pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia‐ene reaction has been developed. Depending on the nitroalkene, the 5‐exo‐dig‐cyclization could be achieved by silver‐catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments. 相似文献
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The biocatalytic system comprised of RizA and acetate kinase (AckA) combines the specific synthesis of bioactive arginyl dipeptides with efficient ATP regeneration. Immobilization of this coupled enzyme system was performed and characterized in terms of activity, specificity and reusability of the immobilisates. Co-immobilization of RizA and AckA into a single immobilisate conferred no disadvantage in comparison to immobilization of only RizA, and a small addition of AckA (20:1) was sufficient for ATP regeneration. New variants of RizA were constructed by combining mutations to yield variants with increased biocatalytic activity and specificity. A selection of RizA variants were co-immobilized with AckA and used for the production of the salt-taste enhancers Arg-Ser and Arg-Ala and the antihypertensive Arg-Phe. The best variants yielded final dipeptide concentrations of 11.3 mM Arg-Ser (T81F_A158S) and 11.8 mM Arg-Phe (K83F_S156A), the latter of which represents a five-fold increase in comparison to the wild-type enzyme. T81F_A158S retained more than 50% activity for over 96 h and K83F_S156A for over 72 h. This study provides the first example of the successful co-immobilization of an l-amino acid ligase with an ATP-regenerating enzyme and paves the way towards a bioprocess for the production of bioactive dipeptides. 相似文献
104.
The Superacid HBr/AlBr3: Protonation of Benzene and Ordered Crystal Structure of [C6H7]+[Al2Br7]− 下载免费PDF全文
Dipl.‐Chem. Franziska Scholz Dr. Daniel Himmel B. Sc. Lea Eisele B. Sc. Wiebke Unkrig Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2014,53(6):1689-1692
Crystalline and properly ordered protonated benzene as the [C6H7]+[Al2Br7]??(C6H6) salt 1 are obtained by the combination of solid AlBr3, benzene, and HBr gas. Compound 1 was characterized and verified by NMR, Raman and X‐Ray spectroscopy. This unexpected simple and straight forward access shows that HBr/AlBr3 is an underestimated superacid that should be used more frequently. 相似文献
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Sylvestre P. J. T. Bachollet Dr. Daniel Volz Béla Fiser Stephan Münch Dr. Franziska Rönicke Dr. Jokin Carrillo Harry Adams Prof. Ute Schepers Enrique Gómez‐Bengoa Prof. Stefan Bräse Prof. Joseph P. A. Harrity 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12430-12438
Ten borylated bipyridines (BOBIPYs) have been synthesized and selected structural modifications have been made that allow useful structure–optical property relationships to be gathered. These systems have been further investigated using DFT calculations and spectroscopic measurements, showing blue to green fluorescence with quantum yields up to 41 %. They allow full mapping of the structure to determine where selected functionalities can be implemented, to tune the optical properties or to incorporate linking groups. The best derivative was thus functionalised with an alkyne linker, which would enable further applications through click chemistry and in this optic, the stability of the fluorophores has been evaluated. 相似文献
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