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Abstract
This dissertation presents three projects centered on stereoselective synthesis of organoboronates, with one project focusing on ligand development and the other two on the synthesis of stereodefined cyclic compounds.
First, we have developed an enantioselective Pd-catalyzed conjunctive cross-coupling reaction through the use of electronically non-symmetric phosphino-oxazoline ligands. This tunable ligand scaffold shows great catalytic performance and facilitates the use of Grignard-derived boron “ate” complexes without requiring additional additives. Additionally, this catalytic system serves as a foundation for expanding the scope of conjunctive cross-coupling reactions.
Second, we have developed an enantioselective Pd-catalyzed intramolecular conjunctive cross-coupling reaction through the use of the newly optimized palladium/phosphino-oxazoline catalyst system. The in situ generated cyclic boron “ate” complex underwent a 1,2-shift, coupling efficiently with a variety of aryl, alkynyl, and benzyl electrophiles to afford stereodefined carbocyclic and heterocyclic tertiary boronic esters in high yield and enantioselectivity.
Finally, we have investigated the polyene cyclization reaction with 1,4-allyl bis(boronates). N-Iodosuccinimide was found to effectively trigger intramolecular cyclization of a variety of different 1,4-allyl bis(boronates) in high diastereoselectivity. This method offered a simple and efficient route to access cyclic terpene-type derivatives with functional groups for further transformation. More development of its synthetic utility is currently underway.
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