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New Aspects of the Double Interrupted and Vinylogous Nazarov Cyclization
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- Author / Creator
- Karpov, Yury
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Developing diverse effective synthetic tools to generate structural complexity in molecular frameworks is considered an attractive area of pursuit. Among those tools, the Nazarov reaction is an effective route towards the generation of complex polycyclic skeletons like five-membered rings, which are widely met phenomena in potential drug candidates. The Nazarov reaction plays an important role plays an important role in the synthesis of highly functionalized cyclopentanones from 1,4-dien-3-ones with the application of Lewis acids. This dissertation will discuss new aspects of the double interruption of the Nazarov cyclization initiated by organoaluminum reagents as well as the interrupted vinylogous Nazarov cyclization.
Chapter 1 describes strategies of intra- and intermolecular trapping of the Nazarov cyclization intermediate, along with recent successful examples to access cyclopentanoid products. This chapter will have a detailed recount of methods that use a variety of traps in both fashions, providing molecular complexity with a step economy.
Chapter 2 discusses a one-pot double interrupted Nazarov sequence, which leads to the formation of the substituted α-halocyclopentanones. Organoaluminum serves as reaction initiator, a source of a nucleophile to trap an oxyallyl cation, and is proposed to deliver an electrophile closer to the aluminum enolate.
Chapter 3 describes the first example of the interrupted vinylogous Nazarov reaction. The use of intramolecular trapping allows the rapid formation of complex compounds. The intermolecular interrupted vinylogous Nazarov cyclization mediated by different Lewis acids provides different trapping products. The trapping studies allows a deeper understanding of the reaction mechanism.
A new approach to access butenolides from [3]dendralenes will be disclosed in Chapter 4. This unexpected result was obtained during attempts to perform the intramolecular interrupted vinylogous Nazarov cyclization. Preliminary results on reaction scope will be included in this chapter.
Chapter 5 tells the story of the Meyer–Schuster/Nazarov cascade reaction development, in which the rearrangement of propargylic alcohol is combined efficiently with the subsequent electrocyclization. Future plans for chapters 2–5 will be discussed, as well. -
- Graduation date
- Fall 2020
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
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