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1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids.

Record Type:	Electronic resources : Monograph/item
Title/Author:	1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids.
Author:	Shepard, Stacey.
Description:	630 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2680.
Notes:	Supervisor: Jeffrey David Winkler.
Contained By:	Dissertation Abstracts International64-06B.
Subject:	Chemistry, Organic.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3095941
ISBN:	0496435663

1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids.
Shepard, Stacey.

1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids. [electronic resource] - 630 p.

Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2680.

Thesis (Ph.D.)--University of Pennsylvania, 2003.

A second-generation strategy proposed a crossed photocycloaddition of a 1,5-hexadiene. To access this photosubstrate, the vinylogous Wolff rearrangement (VWR) was investigated. An alpha-diazo-beta-ketoester VWR precursor was also examined which resulted in dramatically improved yields of rearranged products. The resulting gamma,delta-unsaturated ester was elaborated into a diisopropyliminooxazinone-containing photosubstrate, irradiation of which afforded the unexpected product arising from the straight mode of photocycloaddition.

ISBN: 0496435663Subjects--Topical Terms:

193634
Chemistry, Organic.

1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids.
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245 1 0 $a 1. Studies directed toward the total synthesis of aphidicolin. 2. A ring-metathesis cascade approach to novel rigid scaffolds derived from beta-amino acids. $h [electronic resource]
300 $a 630 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-06, Section: B, page: 2680.
500 $a Supervisor: Jeffrey David Winkler.
502 $a Thesis (Ph.D.)--University of Pennsylvania, 2003.
520 # $a A second-generation strategy proposed a crossed photocycloaddition of a 1,5-hexadiene. To access this photosubstrate, the vinylogous Wolff rearrangement (VWR) was investigated. An alpha-diazo-beta-ketoester VWR precursor was also examined which resulted in dramatically improved yields of rearranged products. The resulting gamma,delta-unsaturated ester was elaborated into a diisopropyliminooxazinone-containing photosubstrate, irradiation of which afforded the unexpected product arising from the straight mode of photocycloaddition.
520 # $a During construction of a 1,6-heptadiene precursor for straight photocycloaddition, a new method for the intact installation of the dioxenone chromophore into photosubstrates via conjugate addition of beta-ketoesters to a vinyl dioxenone was developed.
520 # $a The second section describes the construction of novel rigid tricyclic scaffolds which have potential application as peptidomimetics. A ring-opening-closing cascade olefin metathesis of oxabicyclo[2.21]heptene-containing beta-amino acids afforded stereochemically complex scaffolds possessing two olefins which could be functionalized with groups important for recognition by a receptor of interest. Preliminary investigations of the metathesis of a beta-peptide dimer to a pentacyclic scaffold, including application of a salicylaldehyde-tethered strategy to circumvent the difficulty of medium-ring lactam formation, are also described.
520 # $a This dissertation describes two independent research projects. The first section describes studies directed toward the total synthesis of aphidicolin, highlighting intramolecular dioxenone [2+2] photocycloaddition. This work demonstrates the utility of this methodology in the placement of an extraordinarily hindered C-9 quaternary stereocenter in the natural product, and broadens the scope of useful transformations for the introduction of the dioxenone chromophore into photosubstrates.
520 # $a Transient B-ring opening alleviated steric hindrance at the C-9 ketone in the construction of a dioxenone-containing precursor to crossed photocycloaddition. Olefin and dioxenone moieties were installed at the open stage. Intramolecular Heck and radical cyclizations were explored for B-ring closure at the delta-position of the unsaturated dioxenone moiety. Radical cyclization furnished the dioxenone-containing photosubstrate, irradiation of which similarly afforded the straight photoadduct, contrary to the "rule of fives."
590 $a School code: 0175.
650 # 0 $a Chemistry, Organic. $3 193634
710 0 # $a University of Pennsylvania. $3 212781
773 0 # $g 64-06B. $t Dissertation Abstracts International
790 $a 0175
790 1 0 $a Winkler, Jeffrey David, $e advisor
791 $a Ph.D.
792 $a 2003
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