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511.
Erica E. Schultz Nathaniel R. Braffman Michael U. Luescher Harry H. Hager Emily P. Balskus 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(10):3183-3187
The Friedel–Crafts alkylation is commonly used in organic synthesis to form aryl–alkyl C?C linkages. However, this reaction lacks the stereospecificity and regiocontrol of enzymatic catalysis. Here, we describe a stereospecific, biocatalytic Friedel–Crafts alkylation of the 2‐position of resorcinol rings using the cylindrocyclophane biosynthetic enzyme CylK. This regioselectivity is distinct from that of the classical Friedel–Crafts reaction. Numerous secondary alkyl halides are accepted by this enzyme, as are resorcinol rings with a variety of substitution patterns. Finally, we have been able to use this transformation to access novel analogues of the clinical drug candidate benvitimod that are challenging to construct with existing synthetic methods. These findings highlight the promise of enzymatic catalysis for enabling mild and selective C?C bond‐forming synthetic methodology. 相似文献
512.
The photophysics of trimethylamine (TMA) and rare gas-TMA van der Waals molecules has been studied under supersonic beam conditions. Dual exponential fluorescence decays observed for excitation of the second excited singlet state (S2) are attributed to a novel S2-S1 relaxation induced by the vibrational predissociation of van der Waals molecules. 相似文献
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514.
Temperature dependence measurements (2–77°K) of both the lifetime of decay and the quantum yield of luminescence for the tris(2,2′-bipyridine)ruthenium(II) cation show the emission to originate from several levels. Energy level gaps, rate constants, and quantum yields have been measured for each individual level, and group theoretical symmetry assignments have been made on the basis of a proposed electronic coupling model. 相似文献
515.
516.
Markus J. Barthel Krzysztof Babiuch Tobias Rudolph Jürgen Vitz Stephanie Hoeppener Michael Gottschaldt Martin D. Hager Felix H. Schacher Ulrich S. Schubert 《Journal of polymer science. Part A, Polymer chemistry》2012,50(14):2914-2923
A well‐defined triblock terpolymer, poly(ethylene glycol)‐block‐poly(allyl glycidyl ether)‐block‐poly(tert‐butyl glycidyl ether) (PEG‐b‐PAGE‐b‐Pt‐BGE), with a narrow molar mass distribution has been synthesized by sequential living anionic ring‐opening polymerization. Afterward, the PAGE block was modified via thiol‐ene chemistry and different sugar moieties or cysteine as a model compound for peptides could be covalently attached to the polymer backbone. The solution self‐assembly of the obtained bis‐hydrophilic triblock terpolymers in aqueous media has been studied in detail by turbidimetry, dynamic light scattering, and transmission electron microscopy (TEM and cryo‐TEM). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献