UCLA

This dissertation focuses on the development of catalytic Carbon to Carbon (C–C) bond forming reactions of dicoordinate carbocations. The unique reactivity described herein focuses on the use of ionizable groups and appropriate counter anions to facilitate productive reactions of high-energy cationic intermediates. The first chapter discusses the exploration of phenyl carbocations, generated from aryl fluorides under silylium-weakly coordinating anion (WCA) catalysis, in the context of hydrocarbon functionalization. Chapter two describes the discovery of C–H insertion and reductive Friedel-Crafts reactions of vinyl carbocations generated from vinyl triflates and silylium-WCA salts. Chapter three describes a novel approach to generating vinyl cations using Lithium Lewis acids. Interestingly, these vinyl carbocations are formed under basic conditions, with lithium hexamethyldisilazide (LiHMDS) as the Lewis acid precursor. Chapter four describes two new catalytic manifolds using urea-based organocatalysts. In one instance, the urea catalyst directly ionizes the vinyl triflate through a hydrogen-bonding interaction to promote intra molecular C–H insertion reactions. In another case, urea organocatalysts combined with LiHMDS, result in novel lithium-urea catalyst that promote Friedel-Crafts reactions of vinyl triflates. In summary, these studies have resulted in the development of new catalytic methods using main-group catalysis for the formation of C–C bonds.