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Catalytic Methods for Dearomatization and Chemoselective Amide Reduction
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Catalytic Methods for Dearomatization and Chemoselective Amide Reduction. |
| 개인저자 | Peruzzi, Michael T. |
| 단체저자명 | The University of North Carolina at Chapel Hill. Chemistry. |
| 발행사항 | [S.l.]: The University of North Carolina at Chapel Hill., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 254 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781088306864 |
| 학위논문주기 | Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Gagne, Michel R |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | Catalytic methods for dearomatization transform readily available achiral molecules into stereochemically and functionally rich building blocks. Current methods for dearomatization are typically coupled to strongly enthalpically favorable processes to compensate for the loss of aromaticity. In contrast we have developed a dearomatizing rearrangement facilitated by the favorable thermodynamics of a Claisen rearrangement. The aromatic Claisen rearrangement was catalyzed by electrophilic Au(I) catalysts under mild conditions generating valuable all-carbon stereogenic centers adjacent to a carbonyl. Allyl, allenyl, and propargyl, naphthyl ethers underwent the desired rearrangement in good yields. The more challenging phenyl ether rearrangement required trapping of a reactive cyclohexadienone via a Diels-Alder trapping scheme to complete the dearomatization. Unfortunately, the scope of the phenyl ether rearrangement was limited. Additionally, we found that an enantioselective version of the dearomatization reaction could only be accessed with low enantioselectivities.Traditional methods for the synthesis of amines from amides often requires stoichiometric amounts of strong reducing agents, however these harsh conditions are incompatible with many functional groups. More recently, catalytic methodologies utilizing mild silane reductants have been developed and display excellent chemoselectivities. We found that heteroleptic fluroaryl borane catalysts can efficiently reduce tertiary alkyl amides and benzamides (and some cases secondary amides). The catalytic system described exhibits exceptional chemoselectivity in the reduction of oligoamides and tolerates functionalities which are prone to reduction under similar conditions.The successful application of heteroleptic fluoroaryl boranes as catalysts for chemoselective amide reduction prompted us to explore their utility in terms of site selectivity. To this end we developed novel site-selective reductions of the cyclic undecapeptide cyclosporine A. Tertiary silane Me2EtSiH provides two unique cyclosporine A derivatives, one of which can be readily diversified in subsequent reactions. The secondary silane Et2SiH2 enables divergent reactivity that uses a free hydroxyl group to direct the reduction. The transient O-silyl hemiaminal intermediate of this reduction can additionally be trapped by reducing to the amine or by reductive cyanation. |
| 일반주제명 | Organic chemistry. Catalysts. Chemical engineering. |
| 언어 | 영어 |
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