Enantiospecific CH Activation Using Ruthenium Nanocatalysts
作者:Céline Taglang、Luis Miguel Martínez-Prieto、Iker del Rosal、Laurent Maron、Romuald Poteau、Karine Philippot、Bruno Chaudret、Serge Perato、Anaïs Sam Lone、Céline Puente、Christophe Dugave、Bernard Rousseau、Grégory Pieters
DOI:10.1002/anie.201504554
日期:2015.9.1
The activation of CH bonds has revolutionized modern synthetic chemistry. However, no general strategy for enantiospecificCHactivation has been developed to date. We herein report an enantiospecificCHactivation reaction followed by deuterium incorporation at stereogenic centers. Mechanistic studies suggest that the selectivity for the α‐position of the directing heteroatom results from a four‐membered
Synthesis of [4-2H2]-, (4R)[4-2H1]- and (4S)[4-2H1]- 4-(methylnitrosamino)-1-(3'-pyridyl)-1-butanone, c-4 deuteriated isotopomers of the procarcinogen nnk
作者:Tanmaya Pathak、Noel F. Thomas、Mahmoud Akhtar、David Gani
DOI:10.1016/s0040-4020(01)81978-5
日期:1990.1
The synthesis of C-4 dideuteriated and both C-4 monodeuteriated enantiomers of NNK, the metabolic precursor to a variety of potential carcinogens, starting from (2S)-glutamic acid and nicotinic acid is described. The route is suitable for the synthesis of NNK isotopomers labelled in each of the putative sites for metabolic activation.
Investigations of the Alignment Process of PBPMLG:
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H NMR Analysis Reveals a Thermoresponsive 90° Flip of the Polymer
作者:Dominic S. Schirra、Max Hirschmann、Iliya A. Radulov、Matthias Lehmann、Christina M. Thiele
DOI:10.1002/anie.202108814
日期:2021.9.13
understanding of the alignment process. We present one approach for investigating the thermoresponsive behavior by synthesizing specifically deuterated PBPMLG-isotopologues and their subsequent analyses using 2H NMR-spectroscopy. It was possible to relate the observed thermoresponsive behavior to a flip of the polymer with respect to the external magnetic field—an effect never observed before in glutamate-based
Cyclosporin A-induced free radical generation is not mediated by cytochrome P-450
作者:Alexandra Krauskopf、Timo M Buetler、Nathalie S D Nguyen、Katherine Macé、Urs T Ruegg
DOI:10.1038/sj.bjp.0704544
日期:2002.2
Reactive oxygen species (ROS) have been proposed to play a role in the side effects of the immunosuppressive drug cyclosporin A (CsA).The aim of this study was to investigate whether cytochrome P‐450 (CYP) dependent metabolism of CsA could be responsible for ROS generation since it has been suggested that CsA may influence the CYP system to produce ROS.We show that CsA (1 – 10 μM) generated antioxidant‐inhibitable ROS in rat aortic smooth muscle cells (RASMC) using the fluorescent probe 2,7‐dichlorofluorescin diacetate.Using cytochrome c as substrate, we show that CsA (10 μM) did not inhibit NADPH cytochrome P‐450 reductase in microsomes prepared from rat liver, kidney or RASMC.CsA (10 μM) did not uncouple the electron flow from NADPH via NADPH cytochrome P‐450 reductase to the CYP enzymes because CsA did not inhibit the metabolism of substrates selective for several CYP enzymes that do not metabolize CsA in rat liver microsomes.CsA (10 μM) did not generate more radicals in CYP 3A4 expressing immortalized human liver epithelial cells (T5‐3A4 cells) than in control cells that do not express CYP 3A4.Neither diphenylene iodonium nor the CYP 3A inhibitor ketoconazole were able to block ROS formation in rat aortic smooth muscle or T5‐3A4 cells.These results demonstrate that CYP enzymes do not contribute to CsA‐induced ROS formation and that CsA neither inhibits NADPH cytochrome P‐450 reductase nor the electron transfer to the CYP enzymes.British Journal of Pharmacology (2002) 135, 977–986; doi:10.1038/sj.bjp.0704544
Approach was developed to a preparative synthesis of isotope-labeled aminoacids contained in servamycin IIB antibiotic. Glutamines labeled with N-15, C-13, and H-2 were prepared in 70-80% yield starting with the corresponding labeled glutamic. acids under catalysis with the glutamine synthetase enzyme. N-15-2-aminoisobutanoic acid and N-15-isovaline were obtained by Strecker method in 65 and 31% yields respectively. All compounds synthesized were identified and characterized by NMR spectroscopy.