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Organoytterbium ate complexes extend the value of cyclobutenediones as isoprene equivalents

Organoytterbium ate complexes extend the value of cyclobutenediones as isoprene equivalents
Organoytterbium ate complexes extend the value of cyclobutenediones as isoprene equivalents
3-Methyl-4-alkoxycyclobuten-1,2-diones have long been recognised as valuable isoprene equivalents. Being readily introduced to a substrate as the electrophilic component in an organolithium addition reaction, the thermochemical rearrangement of the resulting adducts give access to quinones, benzoquinones and a host of heteroaromatic ring systems. Importantly, the differential reactivity of the carbonyl groups in 3-methyl-4-alkoxycyclobuten- 1,2-diones provides a reliable means of introducing the isoprene unit in a regiocontrolled manner. However, this feature also imposes a severe limitation, as it allows access to just one regioisomeric series of the products. Herein we detail a simple solution to this longstanding problem that makes use of a hitherto unknown facet of organoytterbium reactivity. In essence, while organolithium reagents favour addition to the C-1 carbonyl of 3-methyl-4 methoxycyclobuten-1,2-dione, the corresponding organoytterbium reagents give near exclusive addition to the C-2 carbonyl of 3-methyl-4-tbutoxycyclobuten- 1,2-dione. The dichotomy extends to a broad spectrum of organolithium and ytterbium reagents (Me, 1°-, 2°- and 3° alkyl, vinyl, aryl, hetaryl and alkynyl), providing access to both regioisomeric series of quinones and benzoquinones without recourse to a cumbersome protecting group strategy. The method has been exemplified with the first total synthesis of the quinone-based natural product (–) mansonone B.
Packard, Emma
996d6dd2-803e-4892-8f88-f97b123a8ed4
Packard, Emma
996d6dd2-803e-4892-8f88-f97b123a8ed4
Harrowven, David
bddcfab6-dbde-49df-aec2-42abbcf5d10b

Packard, Emma (2014) Organoytterbium ate complexes extend the value of cyclobutenediones as isoprene equivalents. University of Southampton, Chemistry, Doctoral Thesis, 364pp.

Record type: Thesis (Doctoral)

Abstract

3-Methyl-4-alkoxycyclobuten-1,2-diones have long been recognised as valuable isoprene equivalents. Being readily introduced to a substrate as the electrophilic component in an organolithium addition reaction, the thermochemical rearrangement of the resulting adducts give access to quinones, benzoquinones and a host of heteroaromatic ring systems. Importantly, the differential reactivity of the carbonyl groups in 3-methyl-4-alkoxycyclobuten- 1,2-diones provides a reliable means of introducing the isoprene unit in a regiocontrolled manner. However, this feature also imposes a severe limitation, as it allows access to just one regioisomeric series of the products. Herein we detail a simple solution to this longstanding problem that makes use of a hitherto unknown facet of organoytterbium reactivity. In essence, while organolithium reagents favour addition to the C-1 carbonyl of 3-methyl-4 methoxycyclobuten-1,2-dione, the corresponding organoytterbium reagents give near exclusive addition to the C-2 carbonyl of 3-methyl-4-tbutoxycyclobuten- 1,2-dione. The dichotomy extends to a broad spectrum of organolithium and ytterbium reagents (Me, 1°-, 2°- and 3° alkyl, vinyl, aryl, hetaryl and alkynyl), providing access to both regioisomeric series of quinones and benzoquinones without recourse to a cumbersome protecting group strategy. The method has been exemplified with the first total synthesis of the quinone-based natural product (–) mansonone B.

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Published date: 31 January 2014
Organisations: University of Southampton, Chemistry

Identifiers

Local EPrints ID: 362641
URI: http://eprints.soton.ac.uk/id/eprint/362641
PURE UUID: a8082c9b-4ac5-477b-aee3-cd5ef7ee09f0
ORCID for David Harrowven: ORCID iD orcid.org/0000-0001-6730-3573

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Date deposited: 03 Mar 2014 14:02
Last modified: 14 Dec 2018 01:37

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Contributors

Author: Emma Packard
Thesis advisor: David Harrowven ORCID iD

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