Cyanide-catalyzed C-C bond formation : synthesis of novel compounds, materials and ligands for homogeneous catalysis /
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| Format: | Thesis eBook |
| Language: | English |
| Published: |
[College Station, Tex.] :
[Texas A&M University],
[2007]
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| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Abstract: | Cyanide-catalyzed aldimine coupling was employed to synthesize compounds with 1,2-ene-diamine and [alpha]-imine-amine structural motifs: 1,2,N,N'-tetraphenyletheylene-1,2-diamine (13) and (+/-)-2,3-di-(2-hydroxyphenyl)-1,2-dihydroquinoxaline (17), respectively. Single crystal X-ray diffraction provided solid state structures and density functional theory calculations were used to probe isomeric preferences within this and the related hydroxy-ketone/ene-diol system. The ene diamine and imine-amine core structures were calculated to be essentially identical in energy. However, additional effects-such as [pi] conjugation-in 13 render an ene-diamine structure that is slightly more stable than the imine-amine tautomer (14). Incontrast, the intramolecular hydrogen bonding present in 17 significantly favors the imine-amine isomer over the ene-diamine tautomer (18). Aldimine coupling (AIC) is the nitrogen analogue of the benzoin condensation and has been applied to dialdimines, providing the first examples of cyclizations effected by cyanide-catalyzed AIC. Sodium cyanide promoted the facile, intramolecular cyclization of several dialdimines in N,N-dimethylformamide, methanol, or dichloromethane/water (phase-transfer conditions) yielding a variety of six-membered heterocycles. Under aerobic conditions, an oxidative cyclization occurs to provide the diimine heterocycle. Cyanide-catalyzed aldimine coupling was employed as a new synthetic method for oligomerization. Nine rigidly spaced dialdimines were oxidatively coupled under aerobic conditions to yield conjugated oligoketimines and polyketimines with unprecedented structure and molecular weight (DP = 2 - 23, ~700 -8200 g/mol). The [alpha]- diimine linkage was established based on IR spectroscopy, NMR spectroscopy, size exclusion chromatography, and X-ray crystallographic characterization of the model oxidized dimer of N-benzylidene-(p-phenoxy)-aniline. Cyclic voltammetry indicates p type electrical conductivity, suggesting they are promising candidates for plastic electronic devices. The cyanide-catalyzed benzoin condensation reaction of 4-substituted benzaldehydes followed by oxidation to the diketone, and the Schiff Base condensation of two equivalents of o-aminophenol provides 2,3-(4-X-phenyl)â‚‚-1,4-(2-hydroxyphenyl)â‚‚-1,4-diazabutadiene. The ligand is given the moniker X-dabphol. These ligands are readily metallated to form M-X-dabphol complexes. The copper complexes catalytically fix COâ‚‚ with propylene oxide to yield propylene carbonate. DFTstudies along with a comparison with Hammet parameters help validate and elaborate on the catalytic cycle and the catalytic results obtained. The nickel complex is competent for olefin epoxidation. Synthesis, characterization, X-ray structure, DFT analysis, and catalytic activity of the parent nickel dabphol complex are reported. |
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| Item Description: | "Major Subject: Chemistry" Title from author supplied metadata (automated record created on Apr. 27, 2007.) Vita. Abstract. Electronic resource. |
| Format: | Mode of access: World Wide Web. System requirements: World Wide Web access and Adobe Acrobat Reader. |
| Bibliography: | Includes bibliographical references. |