Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
2 results
Search Results
Master Thesis Borylation of Petroleum Cracking Olefin Products(01. Izmir Institute of Technology, 2022) Arapoğlu, Mehmet Anıl; Artok, LeventCracking is a process that long-chain hydrocarbons are broken down into more valuable fragments called naphtha cracking products. The olefins formed as a result of this process have various functions such as forming the smallest building blocks of fine and speciality chemicals. It has been foreseen that borylation processes can be applied as a conversion method of these products into valuable intermediate structures. In this context, this thesis describes first time the transition-metal-catalyzed borylation of a number of petroleum cracking olefin products. Borylation reactions have been extensively investigated in the literature and have become one of the popular methods for synthesizing organoboron reagents, which can also be used in the synthesis of functional materials, pharmaceuticals, and agricultural chemicals. In the context of this thesis, petroleum cracking olefinic products were converted into high-value-added organoboron derivatives by metal-catalysed hydroboration and dehydrogenative borylation methods. For this purpose, the experimental conditions were optimized using propene and isobutene reagents. It has been shown in this study that iridium complexes with N-Heterocarbene (NHC) ligands are highly effective catalysts and therefore anti-Markovnikov hydroboration products can be produced in excellent yields even at very low catalyst loadings. On the other hand, alkenyl boron products could be obtained with high yields, which could be performed in the absence of dehydrogenative borylation reactions, ligand, base, and any other additives. The applicability of these methods in internal and terminal alkenes such as cyclohexene, ethene, decene and styrene has been also demonstrated. Finally, these products were converted into a number of intermediates by Suzuki-Miyaura cross-coupling reactions. Thus, in the conversion of alkenes to valuable intermediates, practical and sustainable applications would be possible by using simple, abundant, and cheap reagents instead of expensive and dangerous chemicals.Master Thesis Enantio-Pure Synthesis of Enyne Epoxides and Their Iron-Catalyzed Sn2" Reactions With Grignard Reagents(01. Izmir Institute of Technology, 2020) Omur, Cenk; Artok, LeventThe use of transition-metal catalysts in synthetic chemistry has gained a lot of significance in the last decade, by virtue of their selectivity wheather regio-isomerically, or enantiomerically, or both. Besides their superior selectivity, these reactions have also been considered as atom economic and environmental-friendly. Iron-catalyzed reactions gained undeniable attention in regard to their low toxicity and presence in enzymatic reactions. Thus, use of the iron catalyst in the synthesis of biologically important and intermediary chemicals bear great significance. Allene motifs, which exist in vast number of naturally occuring compounds are important intermediates in synthesis of bio-active materials due to their versatile reactivity and instrict chirality. The first transition metal-mediated sythesis of allenes was accomplished by 1,3-substitution reaction of propargylic acetates with stoichiometric amounts of organocuprates (Rona et al.,1968). Later on, Fürstner and co-workers have established a technique that, allows the use of catalytic amounts of iron complexes for the reaction of Grignard reagents with propargylic oxiranes which yields -allenol compounds with different modes of addition (Fürstner et al., 2003). In addition to significant developments in this field, our group has established iron-promoted reactions of enyne acetates and oxiranes with Grignard reagents, producing functionalized vinyl allene structures. (Taç et al., 2017). In that study, reactions proceeded regioselectively in 1,5-substitution (SN2'') manner yielded vinylallenes in good to high yields. However, stereoselectivity of the method was not sufficiently satisfactory. Nevertheless, we disclose herein that the corresponding iron-catalyzed reactions of enyne oxiranes with an endocyclic alkenyl moiety are highly stereoselective; vinyl allene products could be obtained in high diastereomeric ratios by this method. Moreover, the ability to synthesize oxirane substrates in high enantiomeric purity allowed the production of the desired enantiopure vinyl allenes.