Towards the development of direct methodology to enantioenriched α-alkylated aldehydes
<p>Enantiopure α-alkyl-substituted aldehydes are widely recognised as important building blocks in synthesis. Despite this, methods to prepare such substrates are limited. Strategically, asymmetric intermolecular S<sub>N</sub>2 α-alkylation represents a highly straightforward trans...
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| Format: | Thesis |
| Language: | English |
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2013
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| _version_ | 1826312383872630784 |
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| author | Charlton, A |
| author2 | Hodgson, D |
| author_facet | Hodgson, D Charlton, A |
| author_sort | Charlton, A |
| collection | OXFORD |
| description | <p>Enantiopure α-alkyl-substituted aldehydes are widely recognised as important building blocks in synthesis. Despite this, methods to prepare such substrates are limited. Strategically, asymmetric intermolecular S<sub>N</sub>2 α-alkylation represents a highly straightforward transformation, but still remains an elusive feat. This thesis describes efforts to address this challenge, with attempted access to enantioenriched α-alkyl aldehydes by way of <em>C</em>-alkylation of chiral, non-racemic, hindered aldenamines using simple alkyl halides. Enamines derived from four types of auxiliary (a tropane, an oxazolidine, a pyrrolidine and a homotropane) have been prepared, and their alkylation profile examined.</p> <p>While the desired levels of asymmetric induction were not attained, use of the tropane and homotropane auxiliaries, which differ only by a single methylene group, interestingly, gave complimentary diastereocontrol during alkylation with EtI. The observed stereoselectivity is supported by density functional studies performed for ethylation of both enamines.</p> <p>Additionally, in the course of preparing the homotropane a highly efficient asymmetric synthesis of a homotropinone bearing <em>gem</em>-α-substitution has been developed.</p> |
| first_indexed | 2024-03-07T08:26:42Z |
| format | Thesis |
| id | oxford-uuid:bcfe43bb-1497-4f94-bcc7-6f7c2ae0b3a1 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T08:26:42Z |
| publishDate | 2013 |
| record_format | dspace |
| spelling | oxford-uuid:bcfe43bb-1497-4f94-bcc7-6f7c2ae0b3a12024-02-20T10:34:06ZTowards the development of direct methodology to enantioenriched α-alkylated aldehydesThesishttp://purl.org/coar/resource_type/c_db06uuid:bcfe43bb-1497-4f94-bcc7-6f7c2ae0b3a1Organic chemistryOrganic synthesisEnglishOxford University Research Archive - Valet2013Charlton, AHodgson, D<p>Enantiopure α-alkyl-substituted aldehydes are widely recognised as important building blocks in synthesis. Despite this, methods to prepare such substrates are limited. Strategically, asymmetric intermolecular S<sub>N</sub>2 α-alkylation represents a highly straightforward transformation, but still remains an elusive feat. This thesis describes efforts to address this challenge, with attempted access to enantioenriched α-alkyl aldehydes by way of <em>C</em>-alkylation of chiral, non-racemic, hindered aldenamines using simple alkyl halides. Enamines derived from four types of auxiliary (a tropane, an oxazolidine, a pyrrolidine and a homotropane) have been prepared, and their alkylation profile examined.</p> <p>While the desired levels of asymmetric induction were not attained, use of the tropane and homotropane auxiliaries, which differ only by a single methylene group, interestingly, gave complimentary diastereocontrol during alkylation with EtI. The observed stereoselectivity is supported by density functional studies performed for ethylation of both enamines.</p> <p>Additionally, in the course of preparing the homotropane a highly efficient asymmetric synthesis of a homotropinone bearing <em>gem</em>-α-substitution has been developed.</p> |
| spellingShingle | Organic chemistry Organic synthesis Charlton, A Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title | Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title_full | Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title_fullStr | Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title_full_unstemmed | Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title_short | Towards the development of direct methodology to enantioenriched α-alkylated aldehydes |
| title_sort | towards the development of direct methodology to enantioenriched α alkylated aldehydes |
| topic | Organic chemistry Organic synthesis |
| work_keys_str_mv | AT charltona towardsthedevelopmentofdirectmethodologytoenantioenrichedaalkylatedaldehydes |