Development of the silyl-heck reaction: preparation of organosilanes via the transition metal-catalyzed silylation of alkenes

Abstract

Vinyl and allyl silanes are highly useful reagents in organic synthesis. Due to their nucleophilicity, vinyl and allyl silanes stand out as particularly useful synthetic intermediates that can be applied in many transformations, including Hiyama cross-coupling, Fleming-Tamao oxidation, and Hosomi-Sakurai crotylation. There are a number of routes to access these valuable intermediates. However, prior to our work, few routes could access allyl and vinyl silanes directly from stable, widely available, inexpensive alkenes. We sought to use alkenes as a starting point for vinyl and allyl silane formation, and we have used Heck arylation as our conceptual platform to accomplish this goal. ☐ This dissertation will describe the discovery and development of transition metal-catalyzed methods to form unsaturated organosilanes from simple alkene starting materials and silyl halides. We have developed the first high yielding silyl-Heck reactions of alkenes with silyl halides (X= I, Br, Cl, OTf) to form vinyl silanes, using palladium- and nickel-based catalysts. We have also developed a silyl-Heck reaction to form allyl silanes using palladium catalysis. Additionally, we have developed a synthesis of vinyl silyl ethers from alkenes and silyl ditriflates. Finally, we are working toward developing silyl-Heck-like multi-component reactions of silyl triflates, dialkylzinc reagents, and 1,2- and 1,3-dienes and alkynes to form chiral vinyl and allyl silanes and trisubstituted vinyl silyl ethers.