Asymmetric Diels-Alder reactions of (S)-2-(p-tolylsulfinyl)-1,4-naphthoquinones
摘要:
The asymmetric Diels-Alder reactions of (S)-2-(p-tolylsulfinyl)-1,4-naphthoquinones 1a-c with cyclic dienes have been explored. The high pi facial diastereoselectivity observed can be reversed in the presence of ZnBr2. Evidence is presented to show that the regiochemical outcome of these reactions is controlled only by the sulfinyl group. The in situ cycloaddition/pyrolytic sulfoxide elimination starting from chiral 1a-c offers a convenient new route for the construction of enantiomerically pure 1,4-dihydro-9,10-anthraquinones (+)-10 and (+)-12a-c.
A Small Molecule for Controlled Generation of Reactive Oxygen Species (ROS)
作者:Allimuthu T. Dharmaraja、Harinath Chakrapani
DOI:10.1021/ol403300a
日期:2014.1.17
Due to the short half-life of reactive oxygen species (ROS) such as a superoxide radical, controlled and localized generation of ROS is challenging. Here, we report a rationally designed small-molecule 1c that generates ROS only when triggered by a bacterial enzyme. We provide evidence for 1c predictably enhancing the intracellular superoxide radical in a model bacterium. Spatiotemporal control over ROS generation offered by 1c should help better understand stress responses in bacteria to increased ROS.