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Studies toward the total synthesis o...

University of Pennsylvania.

Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy.
作者:	Waters, Stephen Paul.
面頁冊數:	419 p.
附註:	Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2943.
附註:	Supervisor: Marisa C. Kozlowski.
Contained By:	Dissertation Abstracts International65-06B.
標題:	Chemistry, Organic.
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3138089
ISBN:	0496852590

Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy.
Waters, Stephen Paul.

Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy. - 419 p.

Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2943.

Thesis (Ph.D.)--University of Pennsylvania, 2004.

*Please refer to dissertation for diagrams.

ISBN: 0496852590Subjects--Topical Terms:

193634
Chemistry, Organic.

Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy.
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245 1 0 $a Studies toward the total synthesis of purpuromycin. Synthesis of bisbenzannelated 5,6-spiroketals via a [3+2] dipolar cycloaddition strategy.
300 $a 419 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2943.
500 $a Supervisor: Marisa C. Kozlowski.
502 $a Thesis (Ph.D.)--University of Pennsylvania, 2004.
520 # $a *Please refer to dissertation for diagrams.
520 # $a A new method for the construction of bisbenzannelated spiroketals was developed consisting of [3+2] cycloaddition of nitrile oxides with olefins, reduction of the resulting isoxazoline to beta-keto alcohols (formal aldol products), and subsequent spirocyclization. This method was successfully utilized for the construction of the 5,6-spiroketal core of purpuromycin. Spectroscopic and crystallographic analysis of each diastereomeric spiroketal product, in conjunction with spectroscopic data obtained from a sample of natural purpuromycin, led to an assignment of the hitherto unknown relative configuration of the natural product.*
520 # $a Efficient syntheses of the isocoumarin and naphthalene fragments were established. Key features of the isocoumarin synthesis include the desymmetrization of a functionalized catechol and a Heck coupling/lactonization sequence. Two routes for the naphthalene fragment were established: one based on a Dotz chromium carbene cyclization and the other following a more traditional Diels-Alder approach.
520 # $a Fragment coupling of the fully functionalized isocoumarin and naphthalene fragments of purpuromycin was achieved by the [3+2] cycloaddition protocol. Although subsequent spirocyclization of an advanced intermediate was not realized, the factors responsible for inefficient spiroketal formation were identified through the sequential coupling of each fragment with a suitable model counterpart. While the naphthalene fragment is a willing participant in spirocyclization, the isocoumarin fragment, due to inductive effects from the electron-deficient lactone moiety, is not sufficiently nucleophilic for attack and ring closure. From these findings, a modified synthesis is currently underway in which the isocoumarin fragment is installed in a reduced form prior to spirocyclization.*
520 # $a This dissertation describes studies toward the total synthesis of purpuromycin. Consisting of naphthazarin and isocoumarin ring systems linked through a unique bisbenzannelated 5,6-spiroketal core, purpuromycin shows cytotoxic activity against Gram-positive bacteria, fungi, protozoa, and a number of tumor cell lines.*
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