Browsing by Subject "synthesis"

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    Development of Ti-mediated multicomponent syntheses via cycloaddition and insertion reactions
    (2023-05) Frye, Connor
    Nitrogen-containing compounds are extremely prevalent in bioactive molecules, dyes, electronics, and other materials. Thus, the development of practical synthetic routes to a diverse library of N-containing compounds is vital. Condensation reactions have been traditionally employed to access highly functionalized N-containing compounds. However, these reactions typically exhibit poor chemoselectivity, and frequently require extensive pre-construction of carbon skeletons. These limitations make the development of metal-mediated or -catalyzed multicomponent reactions from simple starting materials an attractive alternative. Given its high abundance and low-cost, Ti is an excellent candidate for facilitating these reactions. Herein, efforts to develop new Ti-mediated or -catalyzed multicomponent transformations for the synthesis of N-containing organic compounds and N-heterocycles are presented. The modular construction of unsymmetrical α-diimines has been achieved through the diimination of alkynes using Ti imidos, nitrosos, and nitriles. This reaction features a key diazatitanacyclohexadiene intermediate, generated ¬in-situ, that undergoes a series of cycloaddition and retrocyclization reactions. The reactivity of this titanacycle towards other unsaturated substrates and electrophiles has been explored, culminating in the development of a multicomponent method for the synthesis of 1,2-dihydropyrimidines. Finally, a newly developed Ti-catalyzed multicomponent synthesis of 2,3-annulated pyrroles from alkynes, 1,2-cyclononadiene, and azobenzene is presented, and the selectivity of other allenes has been assessed. Importantly, all of these Ti-mediated reactions feature key electrocyclic mechanistic steps, and it is becoming increasingly clear that these are a general feature of titanium’s reactivity that can be exploited for the design of new synthetic methods.
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    Synthesis, Characterization, and Investigation of Non-covalent Interactions Between Novel Pyrene-appended Porphyrins and C60
    (2015-09) Wertish, Anthony
    Two different sets of novel pyrene-containing porphyrins were synthesized. The first set, which consists of asymmetric A3B1 and A2B2 porphyrins, was synthesized by the condensation of t-butylphenyl dipyrromethane and newly reported 4-(1-pyrenylmethoxy)benzaldehyde. The second set consists of asymmetric A3B1 and A2B2 porphyrins, which were synthesized by condensation of the dipyrromethane of the newly reported 4-(1-pyrenylmethoxy)benzaldehyde and 1-ferrocenecarboxaldehyde. All four porphyrins were fully characterized by UV-Vis-NIR spectroscopy, NMR spectroscopy, MCD spectroscopy and high-resolution mass spectrometry. Fluorescence spectroscopy studies were performed to qualitatively observe the interactions of the porphyrins with C60 fullerene. It was observed that C60 significantly quenches the fluorescence of pyrene, thus blocking fluorescence, suggesting there is a large amount of interaction between pyrene and C60. DFT and TDDFT calculations were performed in order to further investigate the electronic structure and nature of the excited states of the target porphyrins by first optimizing the equilibrium geometries at the DFT level using the CAM-B3LYP exchange-correlation functional and furthermore using TDDFT. Transient absorption spectroscopy data is being analyzed to elucidate the electron transfer properties of the new porphyrins.