UC Davis

The importance of organosilicon molecules for synthesis and applications increases each year. However, methods to access Si-stereogenic molecules are underexplored. This dissertation includes the development and mechanistic analysis of an organocatalytic method for generating silicon-stereogenic siloxanols from prochiral silanediols. The introduction surveys the properties and applications of silanols. Notable methods for the synthesis of functionalized Si-stereogenic molecules are presented. Finally, the quantification of intermolecular interactions using NMR is briefly discussed. Chapter one will discuss the reaction development of the organocatalytic asymmetric synthesis of siloxanols. A catalyst is selected from a collection of chiral agents, and reaction conditions, including solvent, catalyst loading, reaction time, and acid-scavenging additives, are optimized. The component scope of the reaction and synthetic routes to prochiral silanediols are presented. Chapter two will present the mechanistic analysis of the asymmetric synthesis of siloxanols. An x-ray structure for the catalyst-substrate complex is determined, and catalyst intermolecular interactions are probed by 1H and 29Si NMR titration. Catalyst analogs are synthesized and tested for activity, non-linear effects are ruled out, and attempts to obtain a kinetic profile of the reaction are included. Appendix A will present a collection of work related to the organocatalytic asymmetric synthesis of siloxanols that did not develop into complete projects. Efforts to modify the enantioenriched siloxanol products are discussed. Desymmetrization of symmetrical partially condensed POSS tetraols using the method described in chapters one and two are attempted. Finally, modifications to the organocatalyst to improve catalytic performance are reported.