New Pd and Cu-based catalysts for carbon-heteroatom bond formation
Massachusetts Institute of Technology. Department of Chemistry.
Stephen L. Buchwald.
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The research presented in this dissertation is aimed at the development of novel methodologies for carbon-heteroatom cross-coupling reactions catalyzed by late-transition metals. Both palladium and copper are central to the field of transition metal-catalysis and are integral to the catalyst systems developed as part of our continual advancement in cross-coupling reactions. The first part of this thesis focuses on the use of palladium catalysts to form carbon-sulfur bonds directed towards aryl sulfonamide synthesis. The second part of the thesis describes the recent development in the copper(!) hydride mediated formation of carbon-nitrogen bonds via hydroamination of olefins. Part I. Chapter 1. Palladium-Catalyzed Chlorosulfonylation of Arylboronic Acids Using a biaryl phosphine ligand platform, the first palladium-catalyzed cross-coupling reaction of phenyl chlorosulfate with arylboronic acids was achieved. In this context, the arylsulfonyl chloride products serve as useful precursors to a variety of sulfonyl functional groups, such as aryl sulfonamides, aryl sulfones, and arenesulfonate esters. In particular, this method allows for the preparation of a number of arylsulfonyl chlorides that are not accessible via electrophilic aromatic substitution pathways and under mild reaction conditions. Additionally, this methodology points to an unprecedented selectivity for the phenylchlorosulfate electrophiles used in the cross-coupling reactions. Part II. Chapter 2. Enantio- and Regioselective Copper-Catalyzed Hydroamination of Styrenes and the Extension of the Methodology towards Anti-Markovnikov Hydroamination of Terminal Aliphatic Alkenes The development of a copper-mediated strategy towards the hydroamination of styrene derivatives is reported. In this system, the reaction proceeds regioselectively and enantioselectively to generate [alpha]-branched amines. The system can transform a wide variety of substituted styrenes, including trans-, cis-, and [beta]-disubstituted styrenes. In addition, our extension to copper-catalyzed hydroamination reactions of unactivated aliphatic olefins is reported. Using terminal aliphatic alkenes, the copper-catalyzed hydroamination reactions proceed with anti-Markovnikov regioselectivity. Preliminary results point to the application of this methodology towards [beta]-chiral amine synthesis via the hydroamination of I, 1-disubstituted alkenes. Chapter 3. [alpha]-Aminosilane Synthesis via Copper-Catalyzed Hydroamination of Vinylsilanes The copper-catalyzed hydroamination of vinylsilanes is described. This regioselective reaction generates a-chiral aminosilanes in high yields and enantioselectivities. The method is compatible with differentially substituted vinylsilanes and allows access to many valuable chiral organosilicon compounds. Chapter 4. Synthesis of [gamma]-Chiral Amines via Copper-Catalyzed Hydroamination of 3,3- Disubstituted Allylic Alcohols and 3,3-Disubstituted Allylic Benzoates An investigation into the copper-catalyzed hydroamination of allylic alcohols and allylic benzoates is reported. The reaction proceeds via a [beta]-alkoxy elimination, setting a stereogenic center at the 3-postion to generate [gamma]-chiral amine products. The reaction is more efficient using allylic benzoates. This method is completely regioselective and is applicable to aliphatic allylic benzoates as well as aromatic allylic benzoates. Additionally, we demonstrated that this strategy is applicable towards an allylic epoxide substrate to generate [delta]-chiral amine.
Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2015.Cataloged from PDF version of thesis.Includes bibliographical references.
DepartmentMassachusetts Institute of Technology. Department of Chemistry.
Massachusetts Institute of Technology