relation: http://d-scholarship-dev.library.pitt.edu/9447/
title: Catalytic Asymmetric Synthesis of β-Lactones and Application to the Total Synthesis of (-)-Pironetin
creator: Shen, Xiaoqiang
description: The Al-triamine complex catalyzed acyl halide-aldehyde cyclocondensation (AAC) reactions, developed previously by the Nelson group, have been extended to asymmetric AAC reactions of alkyl-substituted ketenes with structurally diverse aldehydes. By using of 2nd generation Al-triamine complex as catalyst, benzotrifluoride as solvent, the disubstituted β-lactones were synthesized in high yields and excellent enantioselectivities from readily available starting materials.Another conceptionally different methodology has also been developed to synthesize enantioenriched β-lactones. The concept of double activation has been applied in this reaction technology to accelerate the β-lactones formation. By using of cinchona alkaloids to activate ketenes, and at the same time utilizing of lithium salts to activate aldehydes, Wynberg's [2+2] cycloaddition protocol has been greatly expanded to a variety of aldehydes. Stereoenriched β-lactones derived from either Al-triamine or cinchona alkaloids catalyzed asymmetric acyl halide-aldehyde cyclocondensation (AAC) have been untilized in natural product synthesis. An asymmetric total synthesis of the antitumor agent pironetin was pursued using β-lactone templates for establishing all the requisite stereochemical relationships.
date: 2008-01-29
type: University of Pittsburgh ETD
type: PeerReviewed
format: application/pdf
language: en
identifier: http://d-scholarship-dev.library.pitt.edu/9447/1/Shen2007.pdf
identifier:   Shen, Xiaoqiang  (2008) Catalytic Asymmetric Synthesis of β-Lactones and Application to the Total Synthesis of (-)-Pironetin.  Doctoral Dissertation, University of Pittsburgh.    (Unpublished)