Spelling suggestions: "subject:"boronating"" "subject:"boroncontaining""
1 |
Platinum-Catalyzed Enantioselective Diboration of Terminal Alkenes and Vinyl Boronates: Construction of Multiborylated Compounds for Asymmetric SynthesisCoombs, John Ryan January 2015 (has links)
Thesis advisor: James P. Morken / This dissertation will discuss in depth four main projects pertaining to the synthesis and utility of organoboronates for the construction of enantioenriched small molecules. First, reaction optimization and substrate scope expansion of the platinum-catalyzed enantioselective diboration of alkenes are reported. Based on extensive experimental and computational mechanistic analysis, a preliminary stereochemical model is also proposed. A practical boron-Wittig reaction is presented in which synthetically challenging di- and trisubstituted vinyl boronates can be accessed in a highly stereoselective fashion from readily available starting materials. The enantioselective diboration of cis- and trans-vinyl boronates furnished novel 1,1,2-tris(boronate) esters in up to 95:5 er. The intermediate tris(boronate) esters were employed successfully in deborylative alkylations to furnish enantioenriched internal vicinal bis(boronates) in excellent diasteoselectivity. In the final chapter, an enantioselective palladium-catalyzed intramolecular Suzuki-Miyaura coupling between allyl boronates and aryl electrophiles is disclosed. The newly developed transformation provides enantioenriched 5, 6, and 7-membered carbocycles in up to 93:7 er. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
|
2 |
Catalytic Conjunctive Cross-Coupling and Catalytic Diboration ReactionsZhang, Liang January 2017 (has links)
Thesis advisor: James P. Morken / This dissertation will present four main projects focused on stereoselective construction of borylated compounds as well as their applications in asymmetric syntheses. The first two projects describe the development of a catalytic conjunctive cross-coupling reaction. By merging three simple starting materials, an organolithium reagent, an organoboronate, and an organic electrophile, a synthetically valuable secondary boronate is furnished by the conjunctive cross-coupling in an efficient and enantioselective fashion. Next, this strategy is expanded to synthesize severely hindered tertiary boronates, a synthetic challenging but powerful building block to access a variety of quaternary stereocenters. The third project presents a platinum-catalyzed enantioselective diboration of alkenyl boronates to furnish a broad range of 1,1,2-tris(boronates) products. A deborylative alkylation of the 1,1,2-tris(boronates) leads to a variety of internal vicinal bis(boronates) with high diastereoselectivity. In the final chapter, a general and practical synthesis of alkenyl boronates via the boron-Wittig reaction is disclosed. Utilizing readily accessible geminal bis(boronates) and aldehydes, a broad range of disubstituted and trisubstituted alkenyl boronates are afforded with good yield and stereoselectivity. / Thesis (PhD) — Boston College, 2017. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
|
3 |
Stereoselective Synthesis of Organoboron Reagents and their Application Toward the Synthesis of Amphidinolides C and F:Namirembe, Sheila January 2020 (has links)
Thesis advisor: James P. Morken / This dissertation details three main projects that focus on stereoselective synthesis of organoboron reagents and their application to total synthesis studies. The first chapter describes the development of an enantioselective palladium-catalyzed conjuntive cross-coupling of bis(alkenyl)borates to access chiral allylboron reagents. These reagents are of high synthetic value that is demonstrated through various applications. The second chapter describes the development of a diastereoselective amine-modified boron-Wittig reaction with ketone electrophiles to access trisubstituted alkenyl boronic esters. The synthetic utility of these trisubstituted alkenyl boronic esters is demonstrated through a novel palladium-catalyzed cross-coupling reaction. The third chapter encompassess studies toward the total synthesis of natural products amphidinolides C and F. It highlights the application of methods developed in the Morken laboratory in the context of challenging total synthesis. It also highlights the potential for newly developed conjunctive cross-coupling and boron-Wittig reactions to solve problems in total synthesis. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
|
Page generated in 0.0219 seconds