Date of Graduation
Eberly College of Arts and Sciences
1,2,3-Triazole gold (TA--Au) catalysts were developed by Shi's group and employed in several transformations involving propargyl ester rearrangement. Besides the excellent air, moisture and thermal stability introduced through triazole ligands, unique chemoselectivity was observed for these novel Au(I) complexes. The chemoselectivity allowed the effective activation of the alkyne without affecting the reactivity of the allene ester intermediates. These results led to the investigation of the preparation of allene ester intermediates with TA--Au catalysts under anhydrous conditions. As expected, the desired 3,3-rearrangement products were obtained in excellent yields. Besides the typical ester migrating groups, carbonates and carbamates were also found to be suitable for this transformation, which provided a highly efficient, practical method for the preparation of substituted allenes.;Previously research results confirmed TA-Au as a chemoselective catalyst in promoting alkyne activation with high efficiency and improved ligand economy. TA-Au analogues were sequentially revealed as the effective catalysts in promoting allene hydration, giving the enones with excellent yields. Furthermore, the gold-catalyzed intermolecular [2+2] cycloaddition of propargyl esters was achieved with good stereoselectivity. The 'silver-free' condition was critical for this transformation, while only a trace amount of [2+2] products were obtained in the presence of silver under otherwise identical conditions.;Additionally, naphthalene-bridged bis-triazole (NBT) compounds were prepared and characterized for investigation of their photophysical properties. Unlike our previously reported N-2-aryl triazoles (NATs), which gave strong emissions through the planar intramolecular charge transfer mechanism (PICT), this newly developed NBTs adopted a noncoplanar conformation between triazole and naphthalene, achieving fluorescence through twisted intramolecular charge transfer (TICT).
Zhang, Yanwei, "Explore the physical and chemical properties of 1,2,3-triazole: from fluorescence sensor to ligand in metal catalysis" (2015). Graduate Theses, Dissertations, and Problem Reports. 7146.