Herein we report the isolation and characterization of aminal intermediates in the organocatalytic α-chlorination of aldehydes. These species are stable covalent ternary adducts of the substrate, the catalyst and the chlorinating reagent. NMR-assisted kinetic studies and isotopic labeling experiments with the isolated intermediate did not support its involvement in downstream stereoselective processes as proposed by Blackmond. By tuning the reactivity of the chlorinating reagent, we were able to suppress the accumulation of rate-limiting off-cycle intermediates. As a result, an efficient and highly enantioselective catalytic system with a broad functional group tolerance was developed.
The employment of nanogels (NGs) for drug delivery purposes has experienced a huge increase during the last decades. Among the different NGs, those displaying stimuli-responsive properties are of special interest.In particular, NGs that are able to swell or shrink by the action of temperature are very promising materials for applications in the biomedical and biological fields. In this work we present the preparation of thermoresponsive ethylene glycol-based NGs employing a simple and reliable ultrasonication approach.By this means, the reaction times could be shortened and the NGs formation could be performed even at room temperature and in the presence of oxygen. The NGs have been characterized by different techniques and their cloud point could be tuned by changing the molar ratio between the monomers.Finally, the NGs were labelled with Rhodamine B and their cellular uptake and cytotoxicity have been analysed.
A concise and scalable five-step synthesis of vitepyrroloids A and B, two cytotoxic labdane diterpenoid alkaloids from Vitex trifolia, is reported. The presented approach features a Ni-catalyzed cross-electrophile coupling between a (+)-sclareolide-derived alkyl iodide and 3-bromo-2-cyanopyrrole.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.