Development of the first and second-generation Silyl-Heck reactions
Date
2015
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
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.