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Structure-Reactivity Relationships of Lithium Amides : = LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	Structure-Reactivity Relationships of Lithium Amides :/
其他題名:	LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations.
作者:	Mack, Kyle Anthony.
面頁冊數:	1 online resource (195 pages)
附註:	Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Contained By:	Dissertation Abstracts International79-10B(E).
標題:	Organic chemistry. -
電子資源:	click for full text (PQDT)
ISBN:	9780438025660

Structure-Reactivity Relationships of Lithium Amides : = LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations.
Mack, Kyle Anthony.

Structure-Reactivity Relationships of Lithium Amides :LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations. - 1 online resource (195 pages)

Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.

Thesis (Ph.D.)--Cornell University, 2018.

Includes bibliographical references

Enolizations of highly substituted acyclic ketones used in the syntheses of tetrasubstituted olefin-based anticancer agents are described. Lithium hexamethyldisilazide (LiHMDS)-mediated enolizations are moderately Z-selective in neat tetrahydrofuran (THF) and E-selective in 2.0 M THF/hexane. The results of NMR spectroscopy show the resulting enolates to be statistically distributed ensembles of E,E-, E,Z-, and Z,Z-enolate dimers with subunits that reflect the selectivities. The results of rate studies trace the preference for E and Z isomers to tetrasolvated- and pentasolvated-monomer-based transition structures, respectively. Enolization using LiHMDS in N,N-dimethylethylamine or triethylamine in toluene affords a 65:1 mixture of LiHMDS?lithium enolate mixed dimers containing E and Z isomers, respectively. Spectroscopic studies show that condition-dependent complexation of ketone to LiHMDS occurs in trialkylamine/toluene. Rate data attribute the high selectivity exclusively to monosolvated-dimer-based transition structures.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780438025660Subjects--Topical Terms:

1148722
Organic chemistry.
Index Terms--Genre/Form:

554714
Electronic books.

Structure-Reactivity Relationships of Lithium Amides : = LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations.
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245 1 0 $a Structure-Reactivity Relationships of Lithium Amides : $b LiHMDS-Mediated Enolizations of Hindered Aryl Ketones and LiTMP-Mediated Ortholithiations.
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500 $a Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
500 $a Adviser: David B. Collum.
502 $a Thesis (Ph.D.)--Cornell University, 2018.
504 $a Includes bibliographical references
520 $a Enolizations of highly substituted acyclic ketones used in the syntheses of tetrasubstituted olefin-based anticancer agents are described. Lithium hexamethyldisilazide (LiHMDS)-mediated enolizations are moderately Z-selective in neat tetrahydrofuran (THF) and E-selective in 2.0 M THF/hexane. The results of NMR spectroscopy show the resulting enolates to be statistically distributed ensembles of E,E-, E,Z-, and Z,Z-enolate dimers with subunits that reflect the selectivities. The results of rate studies trace the preference for E and Z isomers to tetrasolvated- and pentasolvated-monomer-based transition structures, respectively. Enolization using LiHMDS in N,N-dimethylethylamine or triethylamine in toluene affords a 65:1 mixture of LiHMDS?lithium enolate mixed dimers containing E and Z isomers, respectively. Spectroscopic studies show that condition-dependent complexation of ketone to LiHMDS occurs in trialkylamine/toluene. Rate data attribute the high selectivity exclusively to monosolvated-dimer-based transition structures.
520 $a Rate and mechanistic studies of ortholithiations by lithium 2,2,6,6-tetramethylpiperidine focus on four arenes: 1,4-bis(trifluoromethyl)benzene, 1,3-bis(trifluoromethyl)benzene, 1,3-dimethoxybenzene, and 4,4-dimethyl-2-phenyl-2-oxazoline. Metalations occur via substrate-dependent combinations of monosolvated monomer, disolvated monomer, and tetrasolvated dimer (triple ions). Density functional theory computational studies augment the experimental data. We discuss the challenges presented by shifting dimer--monomer proportions in determining the observable reaction orders and our mathematical treatment of such shifting in reactant structure.
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538 $a Mode of access: World Wide Web
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