Font Size: a A A

Exploring palladium catalysis: From N-tert-prenylation to green chemistr

Posted on:2017-12-23Degree:Ph.DType:Thesis
University:Iowa State UniversityCandidate:Van Zeeland, RyanFull Text:PDF
GTID:2471390017964840Subject:Organic Chemistry
Abstract/Summary:
In this thesis, various palladium-catalyzed reactions to form C-N and C-C are discussed. These reactions span N-tert-prenylation, conjugate addition of arylboronic acids to beta,beta-disubstituted enones and Suzuki-Miyaura cross-coupling of haloarenes and arylboronic acids.;Palladium-catalyzed conjugate addition of wide range of arylboronic acids to beta,beta-disubstituted enones occur to form ketone products bearing benzylic all-carbon quaternary centers. A simple catalyst prepared from palladium trifluoroacetate and 2,2'-bipyridine promotes these reactions. The use of aqueous sodium trifluoroacetate as the reaction medium significantly enhances reactivity and enables formation of challenging bis-benzylic and ortho-substituted benzylic all-carbon quaternary centers.;Palladium(II)-functionalized MOF-253 (MOF-253-Pd(OAc)2) can be used as a recyclable catalyst to form all-carbon quaternary centers via conjugate additions of arylboronic acids to beta,beta-disubstituted enones in aqueous media. MOF-253-Pd(OAc)2 can be reused 8 times to form ketone products in high yields and PXRD confirms the crystallinity remains intact. Additions of a range of stereoelectronically diverse arylboronic acids to a variety of beta,beta-disubstituted enones catalyzed by MOF-253-Pd(OAc) 2 occur in modest-to-high yields.;The electronic and steric effects of linker substitution on the activity of metalated MOFs have been investigated in the context of Suzuki--Miyaura cross-coupling reactions. m-6,6'-Me2bpy-MOF-PdCl2 (UiO-67-Pd-6,6'-dimethyl-bpydc 0.4/bpdc0.6) exhibited a remarkable enhancement in the activity compared to non-functionalized m-bpy-MOF-PdCl2 (UiO-67-Pd-bpydc 0.5/bpdc0.5) and m-4,4'-Me2bpy-MOF-PdCl2 (UiO-67-Pd-4,4'-dimethyl-bpydc0.4/bpdc0.6). This result clearly demonstrates that the stereoelectronic properties of metal-binding linker units are critical to the activity of single-site organometallic catalysts in MOFs.;Three distinct protocols are developed for the synthesis of N-tert-prenylindoles using indole, (eta6-indole)Cr(CO)3, and indoline nucleophiles in the presence of the same catalyst generated from [Pd(eta3-prenyl)Cl] 2 and Xantphos. These reactions form N-tert-prenylindole products with a broad range of substitution and electronic character in high yields with high tert-prenyl-to-n-prenyl selectivity.
Keywords/Search Tags:Form, Reactions, Palladium, Arylboronic acids, All-carbon quaternary centers, Beta-disubstituted enones
Related items