Development of the first and second-generation Silyl-Heck reactions

Watson, Donald A.Allyl and vinylsilanes are important nucleophiles in organic synthesis. They are stable reagents that can participate in a variety of transformations including mainly Hosomi-Sakurai crotylations, Hiyama-Denmark crosscouplings, Tamao-Fleming oxidations, and fluorination reactions. Prior to this work there were few methods that allowed for the synthesis of these valuable compounds from simple alkenes. Using transition metal catalysis, I sought to develop a method to access unsaturated organosilanes using a reaction analogous to the Heck reaction. This endeavor proved valuable, as a powerful new method was developed that allows for the synthesis of vinylsilanes from styrenes and related molecules, and the synthesis of allylsilanes from simple α-olefins containing allylic hydrogen atoms. The latter reaction is highly selective for the linear E-allylsilane. This thesis describes the initial discovery and optimization of the silyl- Heck reaction using palladium catalysis. Methods were developed for use of silyl iodides or silyl chlorides with lithium iodide additives as coupling reagents. The design and synthesis of second-generation ligands have allowed for the synthesis of allylsilanes in high yield by overcoming alkene isomerization. With these ligands I have identified a simplified method to prepare vinyl and allylsilanes. The general transformation has been expanded to nickel catalysis, using silyl triflates as coupling partners without the need for iodide additives.University of Delaware, Department of Chemistry and BiochemistryPh.D