Issue 9, 2001

Stereocontrol in a one-pot procedure for anionic oxy-Cope rearrangement followed by intramolecular aldol reaction

Abstract

Racemic β-hydroxycyclohexanones with up to three chiral centres have been synthesized in a stereocontrolled way using the novel anionic oxy-Cope (AOC) rearrangement of acyclic enol ethers. The first examples of compounds containing an aldehyde and an enol ether in a 1,5 relationship are reported. Stereocontrol in the cyclisation of these compounds by a 6-(enolendo)-exo-trig intramolecular aldol reaction has been studied: there is high stereoselectivity for an axial hydroxy group in the product β-hydroxycyclohexanones. AM1 calculations show that there is a stabilising electrostatic attraction between the oxygen atom of the axial C-3 hydroxy group and the electron-poor carbon at C-1 in the intermediate oxonium ions. ≥87% of AOC rearrangement occurs via a chair-like transition state giving rise to the 5,6-anti stereochemistry of the β-hydroxycyclohexanones. Trapping the enolate product of AOC rearrangement with oxygen gives fragmentation via a 1,2-dioxetane.

Graphical abstract: Stereocontrol in a one-pot procedure for anionic oxy-Cope rearrangement followed by intramolecular aldol reaction

Article information

Article type
Paper
Submitted
19 Dec 2000
Accepted
23 Mar 2001
First published
18 Apr 2001

J. Chem. Soc., Perkin Trans. 1, 2001, 1051-1061

Stereocontrol in a one-pot procedure for anionic oxy-Cope rearrangement followed by intramolecular aldol reaction

A. P. Rutherford, C. S. Gibb, R. C. Hartley and J. M. Goodman, J. Chem. Soc., Perkin Trans. 1, 2001, 1051 DOI: 10.1039/B010138I

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