The use of the n2-aldehyde, ketone and benzyne complexes of Ti and Zr in organic synthesis
The use of the n2-aldehyde, ketone and benzyne complexes of Ti and Zr in organic synthesis
The chemistry of the η2-aldehyde, ketone and benzyne complexes of the early transition metals is reviewed. An intramolecular cocyclisation of unsaturated aldehydes and ketones mediated by the low valent titanium complex [Cp2Ti(PMe3)2] to produce the novel 2-bis(cyclopentadienyl)-1-oxa-2-titanabicyclo[3.3.0]octane and oct-3-ene complexes has been investigated. Elaboration of these complexes with electrophilic reagents was examined as a potential synthetic method for the production of highly functionalised cyclopentanes. The novel zirconocene naphthalyne complexes were found to carbometallate unactivated alkenes and alkynes; when the naphthalyne complexes were trapped in situ with alkenes poor regioselectivity was observed, whilst the corresponding carbometallation of alkynes failed totally. When [PMe3] stabilised zirconocene naphthalyne complexes were treated with alkenes and alkynes good regiocontrol was observed. The synthesis of the A,B,C,D rings of aromatic steroids utilising the [PMe3] stabilised zirconocene naphthalyne complexes was examined; the B,C,D rings of aromatic steroids could also be synthesised using zirconocene benzyne complexes derived from 1-bromoanisole.
University of Southampton
1992
Hewlett, Dudley Francis
(1992)
The use of the n2-aldehyde, ketone and benzyne complexes of Ti and Zr in organic synthesis.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The chemistry of the η2-aldehyde, ketone and benzyne complexes of the early transition metals is reviewed. An intramolecular cocyclisation of unsaturated aldehydes and ketones mediated by the low valent titanium complex [Cp2Ti(PMe3)2] to produce the novel 2-bis(cyclopentadienyl)-1-oxa-2-titanabicyclo[3.3.0]octane and oct-3-ene complexes has been investigated. Elaboration of these complexes with electrophilic reagents was examined as a potential synthetic method for the production of highly functionalised cyclopentanes. The novel zirconocene naphthalyne complexes were found to carbometallate unactivated alkenes and alkynes; when the naphthalyne complexes were trapped in situ with alkenes poor regioselectivity was observed, whilst the corresponding carbometallation of alkynes failed totally. When [PMe3] stabilised zirconocene naphthalyne complexes were treated with alkenes and alkynes good regiocontrol was observed. The synthesis of the A,B,C,D rings of aromatic steroids utilising the [PMe3] stabilised zirconocene naphthalyne complexes was examined; the B,C,D rings of aromatic steroids could also be synthesised using zirconocene benzyne complexes derived from 1-bromoanisole.
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Published date: 1992
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Local EPrints ID: 461016
URI: http://eprints.soton.ac.uk/id/eprint/461016
PURE UUID: 0104476c-27b5-4b61-9464-578f47fc0cfa
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Date deposited: 04 Jul 2022 18:34
Last modified: 04 Jul 2022 18:34
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Author:
Dudley Francis Hewlett
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