Stereoselective reactions of arene chromium tricarbonyl complexes
<p>This thesis describes the application of (arene)Cr(CO)3 methodology to the Stereoselective and enantioselective synthesis of substituted arenes. Chapter one reviews the main methods of preparation and decomplexation of (arene)Cr(CO)<sub>3</sub> complexes and the electronic and...
| मुख्य लेखक: | |
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| अन्य लेखक: | |
| स्वरूप: | थीसिस |
| भाषा: | English |
| प्रकाशित: |
1989
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| विषय: |
| _version_ | 1826301392912908288 |
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| author | Goodfellow, C |
| author2 | Davies, S |
| author_facet | Davies, S Goodfellow, C |
| author_sort | Goodfellow, C |
| collection | OXFORD |
| description | <p>This thesis describes the application of (arene)Cr(CO)3 methodology to the Stereoselective and enantioselective synthesis of substituted arenes. Chapter one reviews the main methods of preparation and decomplexation of (arene)Cr(CO)<sub>3</sub> complexes and the electronic and steric influences of the Cr(CO)<sub>3</sub> unit on the arene.</p> <p>Chapter two demonstrates that the benzylic oxygen directing effect in complexation reactions operates <em>via</em> a direct oxygen bond to the incoming metal unit. Attachment of bulky ft-acceptor groups, such as t-butyldimethylsilyl, to the benzylic oxygen overrides this directing effect.</p> <p>Chapter three describes the regioselective Cl functionalisation of the cryptopine skeleton. Complexation of dihydrocrytopine gives only a single product, the relative configuration of the product being determined using an X-ray crystal structure analysis. Subsequent alkylation of the O-methyl derivative gives Cl alkylated products.</p> <p>Chapter four describes the regioselective <em>ortho</em> functionalisation of ephedrine and pseudoephedrine derivatives. Treatment of (1S,2R)-(N,O-dimethylpseudoephedrine) Cr(CO)<sub>3</sub> with <em>n</em>-butyllithium leads to exclusive removal of the <em>pro-(R) ortho</em> proton. The observed stereoselectivity arises <em>via</em> <p>Chapter five describes the regioselective C4 and C5 functionalisation of (hydrocotarnine)Cr(CO)<sub>3</sub>. Complexation of 1-methylhydrocotarnine occurs to give exclusively the <em>exo</em>-1-methyl derivative. Further functionalisation to give the 1,5- and 4,5-dimethyl products is also described.</p> <p>Chapter six describes the synthesis of <em>ortho</em> substituted (benzaldehyde)Cr(CO)<sub>3</sub> complexes. Chiral material is available via preferential kinetic hydrolysis of, or classical separation of, the L-valinol derived imines.</p> <p>Chapter seven describes the Stereoselective addition of nucleophiles to (<em>o</em>-anisaldehyde) Cr(CO)<sub>3</sub> and (o-trialkylsilylbenzaldehyde)Cr(CO)3. With (<em>o</em>-anisaldehyde)- Cr(CO)<sub>3</sub> the additions are completely stereoselective giving the (<em>RR,SS</em>) diastereoisomer. With (<em>o</em>-trialkylsilylbenzaldehyde)Cr(CO)<sub>3</sub> the ratio of products is influenced by the nature of Lewis acidic species present.</p> <p>Chapter eight describes the Stereoselective benzylic elaboration of (<em>o</em>-methoxybenzyl methyl ether)Cr(CO)<sub>3</sub> achieved via selective removal of the <em>exo</em> benzylic proton from transition states with the methoxy groups <em>anti</em> to each other.</p></p> |
| first_indexed | 2024-03-07T05:31:44Z |
| format | Thesis |
| id | oxford-uuid:e2833156-aec2-42e5-b835-e9ddca4fa27c |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:31:44Z |
| publishDate | 1989 |
| record_format | dspace |
| spelling | oxford-uuid:e2833156-aec2-42e5-b835-e9ddca4fa27c2022-03-27T10:01:46ZStereoselective reactions of arene chromium tricarbonyl complexesThesishttp://purl.org/coar/resource_type/c_db06uuid:e2833156-aec2-42e5-b835-e9ddca4fa27cCarbonyl compoundsChromium compoundsStereochemistryOrganochromium compoundsEnglishPolonsky Theses Digitisation Project1989Goodfellow, CDavies, SDavies, S<p>This thesis describes the application of (arene)Cr(CO)3 methodology to the Stereoselective and enantioselective synthesis of substituted arenes. Chapter one reviews the main methods of preparation and decomplexation of (arene)Cr(CO)<sub>3</sub> complexes and the electronic and steric influences of the Cr(CO)<sub>3</sub> unit on the arene.</p> <p>Chapter two demonstrates that the benzylic oxygen directing effect in complexation reactions operates <em>via</em> a direct oxygen bond to the incoming metal unit. Attachment of bulky ft-acceptor groups, such as t-butyldimethylsilyl, to the benzylic oxygen overrides this directing effect.</p> <p>Chapter three describes the regioselective Cl functionalisation of the cryptopine skeleton. Complexation of dihydrocrytopine gives only a single product, the relative configuration of the product being determined using an X-ray crystal structure analysis. Subsequent alkylation of the O-methyl derivative gives Cl alkylated products.</p> <p>Chapter four describes the regioselective <em>ortho</em> functionalisation of ephedrine and pseudoephedrine derivatives. Treatment of (1S,2R)-(N,O-dimethylpseudoephedrine) Cr(CO)<sub>3</sub> with <em>n</em>-butyllithium leads to exclusive removal of the <em>pro-(R) ortho</em> proton. The observed stereoselectivity arises <em>via</em> <p>Chapter five describes the regioselective C4 and C5 functionalisation of (hydrocotarnine)Cr(CO)<sub>3</sub>. Complexation of 1-methylhydrocotarnine occurs to give exclusively the <em>exo</em>-1-methyl derivative. Further functionalisation to give the 1,5- and 4,5-dimethyl products is also described.</p> <p>Chapter six describes the synthesis of <em>ortho</em> substituted (benzaldehyde)Cr(CO)<sub>3</sub> complexes. Chiral material is available via preferential kinetic hydrolysis of, or classical separation of, the L-valinol derived imines.</p> <p>Chapter seven describes the Stereoselective addition of nucleophiles to (<em>o</em>-anisaldehyde) Cr(CO)<sub>3</sub> and (o-trialkylsilylbenzaldehyde)Cr(CO)3. With (<em>o</em>-anisaldehyde)- Cr(CO)<sub>3</sub> the additions are completely stereoselective giving the (<em>RR,SS</em>) diastereoisomer. With (<em>o</em>-trialkylsilylbenzaldehyde)Cr(CO)<sub>3</sub> the ratio of products is influenced by the nature of Lewis acidic species present.</p> <p>Chapter eight describes the Stereoselective benzylic elaboration of (<em>o</em>-methoxybenzyl methyl ether)Cr(CO)<sub>3</sub> achieved via selective removal of the <em>exo</em> benzylic proton from transition states with the methoxy groups <em>anti</em> to each other.</p></p> |
| spellingShingle | Carbonyl compounds Chromium compounds Stereochemistry Organochromium compounds Goodfellow, C Stereoselective reactions of arene chromium tricarbonyl complexes |
| title | Stereoselective reactions of arene chromium tricarbonyl complexes |
| title_full | Stereoselective reactions of arene chromium tricarbonyl complexes |
| title_fullStr | Stereoselective reactions of arene chromium tricarbonyl complexes |
| title_full_unstemmed | Stereoselective reactions of arene chromium tricarbonyl complexes |
| title_short | Stereoselective reactions of arene chromium tricarbonyl complexes |
| title_sort | stereoselective reactions of arene chromium tricarbonyl complexes |
| topic | Carbonyl compounds Chromium compounds Stereochemistry Organochromium compounds |
| work_keys_str_mv | AT goodfellowc stereoselectivereactionsofarenechromiumtricarbonylcomplexes |