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De Novo Asymmetric Syntheses Of Biologically Active Natural Product, Haibing Guo
De Novo Asymmetric Syntheses Of Biologically Active Natural Product, Haibing Guo
Graduate Theses, Dissertations, and Problem Reports
The enantioselective syntheses of daumone and four analogs have been achieved in 7 to 8 steps. This route relies upon a diasteroselective palladium catalyzed glycosylation reaction for the formation of the anomeric bond. The asymmetry of the sugar and aglycone portion of daumone were introduced by Noyori reduction of an acylfuran and a propargyl ketone. A highly diastereoselective epoxidation and reductive ring opening established the desired C-2 and C-4 stereochemistry of daumone.;A highly enantioselective and stereocontrolled approach to D-, L-swainsonine and 8, 8a-epi-D-swainsonine has been developed from achiral furan or furfural. A one-pot hydrogenolysis, followed by an intramolecular reductive amination …
Synthesis Of Novel Polycyclic Aromatics And Heteroaromatics Via Cascade Cyclizations Of Enyne-Allenes And Enyne-Isocyanates, Hua Yang
Graduate Theses, Dissertations, and Problem Reports
Studies on the thermal cyclization of enyne-isocyanates led to a new synthetic pathway to synthesize heterocycles. It was found that the enyne-isocyanates underwent predominantly C2--C7 cyclization at high temperature and the cycloaromatization was facilitated by the addition of silyl chloride.;The C2--C6 Schmittel cyclization of benzannulated enyne-allenes can provide efficient synthetic pathway for the polycyclic aromatics. As a result, new synthetic pathways to synthesize the 1,2-bis[5-(11 H-benzo[b]fluorenyl)]benzenes and related compounds were developed by employing the Schmittel cyclization reaction. The nonbonded steric interaction led to the formation of syn-isomers as major products, which hold potential to complex with transition metals to catalyze …
Expansion Of The Scope Of The Allenic Pauson-Khand Reaction To Include Carboxylic Acids And Esters, Kimberly D. Fisher
Expansion Of The Scope Of The Allenic Pauson-Khand Reaction To Include Carboxylic Acids And Esters, Kimberly D. Fisher
Graduate Theses, Dissertations, and Problem Reports
1,3,3 Trisubstituted allenes were prepared by performing an SN2' reaction of lactones. Opening of the lactone created carboxylic acids that could then be converted to esters. By varing the functionality on the lactone and the Grignard reagents, a variety of allenes could be prepared to test the viability of the Pauson-Khand reaction in the presence of these functional groups. The positioning of the groups also lead to variations in the system. These reactions produced three different types of adducts. They include alpha-methylene cyclopentenones, 4-alkylidene cyclopentenones, and cross conjugated trienes.*.;*Please refer to dissertation for diagrams.
Novel Synthesis Of 3,4-Fused Indoles, Jeremiah Wallace Hubbard
Novel Synthesis Of 3,4-Fused Indoles, Jeremiah Wallace Hubbard
Graduate Theses, Dissertations, and Problem Reports
The goal of this project was to synthesize 3,4-fused indoles having a variety of ring sizes and a variety of functional groups. This has been accomplished by the development of a novel palladium-catalyzed route to 3,4-fused indoles. The key steps are two palladium-catalyzed reactions, an intramolecular Heck reaction followed by a reductive N-heteroannulation. Using this route, a number of 3,4-fused indoles were prepared in acceptable yields.
Novel Palladium-Catalyzed Synthesis Of 3-Substituted Indoles And Its Application Toward The Total Synthesis Of Indolactam V, Michael Robert Turner
Novel Palladium-Catalyzed Synthesis Of 3-Substituted Indoles And Its Application Toward The Total Synthesis Of Indolactam V, Michael Robert Turner
Graduate Theses, Dissertations, and Problem Reports
A novel synthesis of indoles having electron withdrawing substituents in the 3-position has been developed. Various 2-nitrostyrenes were prepared via Stille coupling of 2-tributyl stannyl-2-propenoic acid ethyl ester with substituted 2-bromo-l-nitrobenzenes. Alternatively, sequential vicarious nucleophilic substitution of substituted nitrobenzenes and Knoevenagel condensation with formaldehyde was used to prepare 2-nitrostyrenes. Palladium catalyzed N-heteroannulation of 2-nitrostyrenes yielded indoles in 61--99%. For example, reaction of a 0.5 M solution of 1,1-dimethylethyl 2-(1-nitro-2-napthyl)propenoate (65) in N,N-dimethylformamide with carbon monoxide (4 atm), in the presence of a catalytic amount of bis(dibenzylideneacetone)palladium(0) (6 mol %), 1,3-bis(diphenylphosphino)propane (6 mol %), and 1,10-phenanthroline monohydrate (12 mol %), gave …