New Synthetic Reactions Involving Epoxonium Ion

With the support of the Chemical Synthesis Program in the Division of Chemistry, Professor Rendy Kartika of Louisiana State University is studying the development of new organic reactions using epoxides. Epoxides are abundant chemical feedstocks that are reactive due to their inherent ring strain. Because of their unique reactivity, epoxides can be readily transformed into value-added chemical derivatives. This award is allowing Professor Rendy Kartika and his team to investigate new chemistries for the synthesis of chlorine-containing organic compounds from epoxides having widespread relevance including in the chemical, pharmaceutical, and materials industries. In addition to their applications, the Kartika group is studying the mechanistic pathways by which the reaction products are formed. In addition to the research, this project is providing valuable training and mentoring opportunities for the next generation of scientists who, in the future, will make valuable contributions to industry, academia, and national laboratories. In addition to training the next generation of researchers, Professor Rendy Kartika is committed to fostering excellence in undergraduate chemistry education at LSU. His activities include efforts to develop new degree initiatives to increase the number of chemistry majors, the modernization of chemistry teaching laboratory instrumental infrastructures and pedagogy, and the creation of a three-semester sequence of General Chemistry for students who require reinforcement of mathematics and chemistry foundation to improve success in this gateway course to STEM degrees. Professor Rendy Kartika and his team at Louisiana State University are examining the reactions of epoxides and related structures in the presence of triphosgene and pyridine. Epoxides are a unique functional group. Due to ring strain, the two adjoining carbon atoms in epoxides are electrophilic. However, the same ring strain also renders epoxides nucleophilic at the oxygen atom. This project is exploiting this dichotomy of reactivity to develop new organic synthetic transformations enabled by triphosgene and pyridine. More specifically, the combination of these reagents activates epoxides to epoxonium ions. These emerging reactive species then undergo nucleophilic ring opening by the chloride ions liberated from triphosgene degradation at the sterically more accessible direction, thereby forging carbon-chlorine bonds. Facilitated by this chemistry, Professor Rendy Kartika is investigating new stereoselective reactions for the synthesis of value-added organochlorine heterocyclic compounds. A particular heterocyclic motif that is a subject of this project are tetrahydropyrans, a six-membered oxygen-containing cyclic structure commonly found in biologically active natural products and pharmaceutical compounds. In addition to focusing on applications and the products from the methodology, this project also features investigations into the reaction mechanisms by which epoxonium ions are formed using in situ NMR spectroscopy techniques. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.