Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis
The design and preparation of a new class of planar chiral ferrocenyl lithium amide bases is described. Work commenced on preparing N./V-dimethyl-l-ferrocenylethylamine derivatives. Electrophilic amination was attempted with a variety of reagents, but no diamines were ever obtained. The introduction...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English |
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2002
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| Online Access: | https://eprints.nottingham.ac.uk/59224/ |
| _version_ | 1848799596612943872 |
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| author | Arnall-Culliford, Jennifer |
| author_facet | Arnall-Culliford, Jennifer |
| author_sort | Arnall-Culliford, Jennifer |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | The design and preparation of a new class of planar chiral ferrocenyl lithium amide bases is described. Work commenced on preparing N./V-dimethyl-l-ferrocenylethylamine derivatives. Electrophilic amination was attempted with a variety of reagents, but no diamines were ever obtained. The introduction of a boronic acid group was also attempted, but no products were isolated. Finally, nitration followed by reduction was investigated, but again proved unsuccessful, resulting only in the preparation of a dimer of the starting amine, 2,2'-bis-[ 1 -(//, A-dimethylamino)-ethyl]-l, l'-biferrocenyl.
Our attention turned to derivatives of MN-diisopropylferrocene carboxamide. Metallation, followed by quenching with iodine gave Af,N-diisopropyl-2- iodoferrocene carboxamide. Copper(I) oxide mediated coupling of the iodide with either acetic acid or phthalimide gave access to ortho-oxygen and nitrogen donor groups. A new class of planar chiral bases (N-alkyl-(2- alkoxyferrocenyl)methylamines) were prepared from this starting material by reduction of the amide, followed by substitution of the diisopropylamine with a range of primary amines.
Assays were carried out using the deprotonation of 4-tert-butylcyclohexanone and trapping of resultant enolate with TMSC1. Bases having a plane of chirality as the only stereochemical element, disappointingly, gave nearly racemic silyl enol ether, however low optical purities were recorded for bases consisting of both central and planar chirality. A non-chelating planar chiral lithium amide base was prepared (^S}-A^-rer/-butyl-(2-methylfen'ocenyl)-t methylamine, however this too gave nearly racemic silyl enol ether in the assay reaction.
The synthesis of planar chiral azaferrocenyl bases was attempted by sequential complexation of lithiated pyrrole-2-methanol and lithium pentamethyl- cyclopentadienide with iron(II) chloride, followed by acylation of the pendant alcohol. However, all attempts to substitute the acetate with an amine proved unsuccessful. |
| first_indexed | 2025-11-14T20:38:11Z |
| format | Thesis (University of Nottingham only) |
| id | nottingham-59224 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T20:38:11Z |
| publishDate | 2002 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-592242025-02-28T12:15:43Z https://eprints.nottingham.ac.uk/59224/ Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis Arnall-Culliford, Jennifer The design and preparation of a new class of planar chiral ferrocenyl lithium amide bases is described. Work commenced on preparing N./V-dimethyl-l-ferrocenylethylamine derivatives. Electrophilic amination was attempted with a variety of reagents, but no diamines were ever obtained. The introduction of a boronic acid group was also attempted, but no products were isolated. Finally, nitration followed by reduction was investigated, but again proved unsuccessful, resulting only in the preparation of a dimer of the starting amine, 2,2'-bis-[ 1 -(//, A-dimethylamino)-ethyl]-l, l'-biferrocenyl. Our attention turned to derivatives of MN-diisopropylferrocene carboxamide. Metallation, followed by quenching with iodine gave Af,N-diisopropyl-2- iodoferrocene carboxamide. Copper(I) oxide mediated coupling of the iodide with either acetic acid or phthalimide gave access to ortho-oxygen and nitrogen donor groups. A new class of planar chiral bases (N-alkyl-(2- alkoxyferrocenyl)methylamines) were prepared from this starting material by reduction of the amide, followed by substitution of the diisopropylamine with a range of primary amines. Assays were carried out using the deprotonation of 4-tert-butylcyclohexanone and trapping of resultant enolate with TMSC1. Bases having a plane of chirality as the only stereochemical element, disappointingly, gave nearly racemic silyl enol ether, however low optical purities were recorded for bases consisting of both central and planar chirality. A non-chelating planar chiral lithium amide base was prepared (^S}-A^-rer/-butyl-(2-methylfen'ocenyl)-t methylamine, however this too gave nearly racemic silyl enol ether in the assay reaction. The synthesis of planar chiral azaferrocenyl bases was attempted by sequential complexation of lithiated pyrrole-2-methanol and lithium pentamethyl- cyclopentadienide with iron(II) chloride, followed by acylation of the pendant alcohol. However, all attempts to substitute the acetate with an amine proved unsuccessful. 2002-12-13 Thesis (University of Nottingham only) NonPeerReviewed application/pdf en arr https://eprints.nottingham.ac.uk/59224/1/251971.pdf Arnall-Culliford, Jennifer (2002) Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis. PhD thesis, University of Nottingham. amide bases; electrophilic amination; chiral bases |
| spellingShingle | amide bases; electrophilic amination; chiral bases Arnall-Culliford, Jennifer Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title | Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title_full | Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title_fullStr | Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title_full_unstemmed | Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title_short | Planar Chiral Ferrocene Lithium Amide Bases: A New Generation of Bases for Asymmetric Synthesis |
| title_sort | planar chiral ferrocene lithium amide bases: a new generation of bases for asymmetric synthesis |
| topic | amide bases; electrophilic amination; chiral bases |
| url | https://eprints.nottingham.ac.uk/59224/ |