Asymmetric Hydrogenation of Ketones and Enones with Chiral Lewis Base Derived Frustrated Lewis Pairs
作者:Bochao Gao、Xiangqing Feng、Wei Meng、Haifeng Du
DOI:10.1002/anie.201914568
日期:2020.3.9
The concept of frustratedLewispairs (FLPs) has been widely applied in various research areas, and metal-free hydrogenation undoubtedly belongs to the most significant and successful ones. In the past decade, great efforts have been devoted to the synthesis of chiral boron Lewis acids. In a sharp contrast, chiral Lewisbase derived FLPs have rarely been disclosed for the asymmetric hydrogenation.
An in situ formed porphyrin-inspired iron complex that catalyzesasymmetricepoxidation of di- and trisubstituted enones is described. The reaction provides highly enantioenriched α,β-epoxyketones (up to 99% ee). The practical utility of the new catalyst system is demonstrated by the gram-scale synthesis of optically pure epoxide. Hammett analysis suggests that the transition state of the reaction
Gerinnungsphysiologische Aktivität von 2-Aryl-2,3,4,5-tetrahydro-1H-benzocyclohepten-1,3-dionen
作者:Klaus Rehse、Thomas Lang、Norbert Rietbrock
DOI:10.1002/ardp.19773101206
日期:——
14 Titelverbindungen wurden synthetisiert. Neun zeigten nach einmaliger oraler Applikation bei Ratten blutgerinnungshemmende Eigenschaften. Fünf verringerten die Gerinnungsfähigkeit des Blutes (Quick‐Zeit) auf weniger als 25% der Norm. Bei 4i (340 mg/kg) wurde dieses Niveau nach 5 h erreicht und 50 h lang aufrechterhalten. Die maximale Verlängerung der Quick‐Zeit wurde hier nach 24 h beobachtet.
Introduction of amino moiety enhances the inhibitory potency of 1-tetralone chalcone derivatives against LPS-stimulated reactive oxygen species production in RAW 264.7 macrophages
作者:Pramila Katila、Aastha Shrestha、Aarajana Shrestha、Ritina Shrestha、Pil-Hoon Park、Eung-Seok Lee
DOI:10.1016/j.bioorg.2019.03.055
日期:2019.6
The design and synthesis of a series of thirty-two halogenated 1-tetralone or 6-amino-1-tetralone chalcone derivatives was achieved by the Claisen-Schmidt condensation reaction and were evaluated for their inhibitory effects against ROS production in LPS-stimulated RAW 264.7 macrophages. It was observed that the introduction of amino moiety into 1-tetralone skeleton greatly increased the inhibitory potency compared to corresponding 1-tetralone chalcones. Among the synthesized compounds, compound 18 which consists of 6-amino-1-tetralone skeleton together with o-fluorobenzylidene showed the most potent ROS inhibitory effect with IC50 value of 0.25 +/- 0.13 mu M. SAR analysis revealed that amino moiety at the 6th position of 1-tetralone chalcones have an important role for exerting the greater ROS inhibitory potency in LPS-stimulated RAW 264.7 macrophages than those exhibited by 1-tetralone chalcones alone.