Doctor of Philosophy (Ph.D.)
Degree Granting Department
Xiaodong Michael Shi, Ph.D.
James Leahy, Ph.D.
Edward Turos, Ph.D.
Libin Ye, Ph.D.
Diyne Activation, Enantioselective, Enyne Cyclization, Gold Catalysis
Homogeneous gold catalysts are known as a powerful tool for selectively activating alkynes and are well-developed in the construction of C-C, C-N, and C-O bonds to form complex compounds that are widely used in pharmaceuticals, industries, agriculture, etc. The investigation of gold(I) catalysis on conjugated diyne (compounds having two acetylene groups) enriches the complexity of the bond construction and allows the building of interesting skeletons in organic synthesis. One typical kind of substrate, diyne-ene, has both a conjugated diyne part and a 1,6- enyne part. We developed a new methodology to allow its divergent synthesis to heterocycles.
This dissertation mainly contains two parts: 1) The gold-catalyzed intramolecular styryl dehydro-Diels–Alder reaction (ISDDA) toward the synthesis of polyaromatic hydrocarbons (PAHs); 2) The gold-catalyzed amine cascade addition to diyne-ene toward the enantioselective synthesis of 1,2-dihydropyridines.
In the first part, the styryl dehydro-Diels–Alder reaction with diyne-ene is reported. While typical alkyne–styrene condensation requires elevated temperatures (>160 °C), the application of a conjugated diyne allowed for effective transformation under milder conditions (80 °C). The thermally stable triazole–gold (TA–Au) catalyst further improved the reaction yields (up to 95%), producing the desired alkynyl–naphthalene in a single step with molecular oxygen as the oxidant. Sequential alkyne activation resulted in various polyaromatic hydrocarbons in excellent yields, highlighting the efficiency of this new strategy for the preparation of PAHs with good functional group tolerance and structural diversity.
In the second part, the gold-catalyzed diyne-ene amination reaction is reported. With the well-documented chemical and biological applications, piperidine and pyridine are among the most important N-heterocycles, and a new synthetic strategy, especially one with an alternative bond-forming design, is of general interest. As the 1,2-dihydropyridine (1,2-DHP) is a valuable synthetic moiety of piperidine and pyridine, its new enantioselective synthesis development is important and urgent. Using the gold-catalyzed intermolecular condensation of amine and diyne-ene, we report herein the first example of enantioselective 1,2-dihydropyridine synthesis through a formal [3+2+1] fashion by gold catalysis with high yields and excellent enantioselectivities.
Scholar Commons Citation
Wei, Jingwen, "Gold-Catalyzed Diyne-ene Cyclization: Synthesis of Hetero Polyaromatic Hydrocarbons and 1,2-Dihydropyridines" (2023). USF Tampa Graduate Theses and Dissertations.