Arene chromium tricarbonyl complexes in synthesis
<p>The work described in this thesis concerns the application of arene chromium tricarbonyl methodology to the stereoselective elaboration of aromatic systems and in particular to the synthesis of homochiral N-methyl-l,2,3,4-tetrahydroisoquinolines. The first chapter deals with the benzylic al...
| Үндсэн зохиолч: | |
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| Бусад зохиолчид: | |
| Формат: | Дипломын ажил |
| Хэл сонгох: | English |
| Хэвлэсэн: |
1989
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| Нөхцлүүд: |
| _version_ | 1826316223182274560 |
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| author | Coote, S |
| author2 | Davies, S |
| author_facet | Davies, S Coote, S |
| author_sort | Coote, S |
| collection | OXFORD |
| description | <p>The work described in this thesis concerns the application of arene chromium tricarbonyl methodology to the stereoselective elaboration of aromatic systems and in particular to the synthesis of homochiral N-methyl-l,2,3,4-tetrahydroisoquinolines. The first chapter deals with the benzylic alkylation of substituted 1,3-dihydroisobenzofurans. Coordination of the precursors to the chromium tricarbonyl unit renders these alkylations stereoselective, thereby permitting a diastereoselective synthesis of c/5-l,3-disubstituted-l,3- dihydroisobenzofurans after decomplexation.</p><p>In the second chapter, the benzylic carbanion stabilising ability of the chromium tricarbonyl fragment is exploited in the enantioselective conversion of (+)-(S)-amphetamine to (+)-(lR,3S,4S)-and(-)-(lS,3S,4R)-l,2,3,4-tetramethyl-l,2,3,4-tetrahydroisoquinoline.</p><p>The modified reactivity of some of the protected derivatives of ephedrine and pseudoephedrine upon coordination to the chromium tricarbonyl moiety is discussed in chapter 3 as a method for the functionalisation of these alkaloids.</p><p>The fourth chapter assesses the stereoselectivity observed in the acid-mediated cyclisation of homochiral N-(3,4-dimethoxybenzyl)halostachine to N-methyl-4-phenyl-6,7- dimethoxy-l,2,3,4-tetrahydroisoquinoline. Complexation of the precursor to the chromium tricarbonyl group renders the cyclisation highly stereoselective. The diastereoselectivity observed in the acid-mediated cyclisation of homochiral N-(substituted-benzyl) phenylpropanolamines to the corresponding 3-methyl-4-phenyl-l,2,3,4- tetrahydroisoquinolines is investigated and the mechanism by which these cyclisations occur is discussed. Coordination of the cyclisation precursors to the chromium tricarbonyl moiety renders the cyclisations completely stereoselective thereby permitting the synthesis of homochiral 4-aryl-1,2,3,4-tetrahydroisoquinolines.</p><p>The last chapter describes an extension of this cyclisation reaction enabling the synthesis of homochiral l-aryl-l,2,4,5-tetrahydrobenzazepines. The stereoselectivity observed in the acid-mediated cyclisation of homochiral N-(3,4-dimethoxyphenethyl)halostachine to Nmethyl- l-phenyl-l,2,4,5-tetrahydrobenzazepine is assessed. The chromium tricarbonyl complex of this cyclisation precursor undergoes a stereoselective cyclisation to furnish the homochiral 1-aryl benzazepine after decomplexation. The diastereoselectivity observed in the acid-mediated cyclisation of homochiral N-3,4-dimethoxyphenethyl phenylpropanolamines is also investigated and the mechanism by which they occur is discussed. Coordination of one of these precursors to the chromium tricarbonyl unit renders the cyclisation stereoselective to give homochiral N-methyl-1 -phenyl-2-methyl-7,8-dimethoxy-1,2,4,5-tetrahydrobenzazepine after decomplexation.</p> |
| first_indexed | 2024-03-06T20:32:30Z |
| format | Thesis |
| id | oxford-uuid:318503a4-e288-4eea-9e11-9f82d26f1b8c |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:41:02Z |
| publishDate | 1989 |
| record_format | dspace |
| spelling | oxford-uuid:318503a4-e288-4eea-9e11-9f82d26f1b8c2024-12-07T11:58:57ZArene chromium tricarbonyl complexes in synthesisThesishttp://purl.org/coar/resource_type/c_db06uuid:318503a4-e288-4eea-9e11-9f82d26f1b8cOrganochromium compoundsChromium compoundsCarbonyl compoundsEnglishPolonsky Theses Digitisation Project1989Coote, SDavies, SDavies, S<p>The work described in this thesis concerns the application of arene chromium tricarbonyl methodology to the stereoselective elaboration of aromatic systems and in particular to the synthesis of homochiral N-methyl-l,2,3,4-tetrahydroisoquinolines. The first chapter deals with the benzylic alkylation of substituted 1,3-dihydroisobenzofurans. Coordination of the precursors to the chromium tricarbonyl unit renders these alkylations stereoselective, thereby permitting a diastereoselective synthesis of c/5-l,3-disubstituted-l,3- dihydroisobenzofurans after decomplexation.</p><p>In the second chapter, the benzylic carbanion stabilising ability of the chromium tricarbonyl fragment is exploited in the enantioselective conversion of (+)-(S)-amphetamine to (+)-(lR,3S,4S)-and(-)-(lS,3S,4R)-l,2,3,4-tetramethyl-l,2,3,4-tetrahydroisoquinoline.</p><p>The modified reactivity of some of the protected derivatives of ephedrine and pseudoephedrine upon coordination to the chromium tricarbonyl moiety is discussed in chapter 3 as a method for the functionalisation of these alkaloids.</p><p>The fourth chapter assesses the stereoselectivity observed in the acid-mediated cyclisation of homochiral N-(3,4-dimethoxybenzyl)halostachine to N-methyl-4-phenyl-6,7- dimethoxy-l,2,3,4-tetrahydroisoquinoline. Complexation of the precursor to the chromium tricarbonyl group renders the cyclisation highly stereoselective. The diastereoselectivity observed in the acid-mediated cyclisation of homochiral N-(substituted-benzyl) phenylpropanolamines to the corresponding 3-methyl-4-phenyl-l,2,3,4- tetrahydroisoquinolines is investigated and the mechanism by which these cyclisations occur is discussed. Coordination of the cyclisation precursors to the chromium tricarbonyl moiety renders the cyclisations completely stereoselective thereby permitting the synthesis of homochiral 4-aryl-1,2,3,4-tetrahydroisoquinolines.</p><p>The last chapter describes an extension of this cyclisation reaction enabling the synthesis of homochiral l-aryl-l,2,4,5-tetrahydrobenzazepines. The stereoselectivity observed in the acid-mediated cyclisation of homochiral N-(3,4-dimethoxyphenethyl)halostachine to Nmethyl- l-phenyl-l,2,4,5-tetrahydrobenzazepine is assessed. The chromium tricarbonyl complex of this cyclisation precursor undergoes a stereoselective cyclisation to furnish the homochiral 1-aryl benzazepine after decomplexation. The diastereoselectivity observed in the acid-mediated cyclisation of homochiral N-3,4-dimethoxyphenethyl phenylpropanolamines is also investigated and the mechanism by which they occur is discussed. Coordination of one of these precursors to the chromium tricarbonyl unit renders the cyclisation stereoselective to give homochiral N-methyl-1 -phenyl-2-methyl-7,8-dimethoxy-1,2,4,5-tetrahydrobenzazepine after decomplexation.</p> |
| spellingShingle | Organochromium compounds Chromium compounds Carbonyl compounds Coote, S Arene chromium tricarbonyl complexes in synthesis |
| title | Arene chromium tricarbonyl complexes in synthesis |
| title_full | Arene chromium tricarbonyl complexes in synthesis |
| title_fullStr | Arene chromium tricarbonyl complexes in synthesis |
| title_full_unstemmed | Arene chromium tricarbonyl complexes in synthesis |
| title_short | Arene chromium tricarbonyl complexes in synthesis |
| title_sort | arene chromium tricarbonyl complexes in synthesis |
| topic | Organochromium compounds Chromium compounds Carbonyl compounds |
| work_keys_str_mv | AT cootes arenechromiumtricarbonylcomplexesinsynthesis |