Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions.
Homochiral beta-amino esters (prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R...
| Main Authors: | , , , , , |
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| Format: | Journal article |
| Language: | English |
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2006
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| _version_ | 1826275567902654464 |
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| author | Davies, S Garner, A Roberts, P Smith, A Sweet, M Thomson, J |
| author_facet | Davies, S Garner, A Roberts, P Smith, A Sweet, M Thomson, J |
| author_sort | Davies, S |
| collection | OXFORD |
| description | Homochiral beta-amino esters (prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one than the corresponding Evans oxazolidin-2-one. A C(4)-iso-propyl stereodirecting group within the oxazinanone conveys higher stereoselectivity than the analogous C(4)-phenyl substituent. gem-Dimethyl substitution at C(6) within the oxazinanone framework facilitates exclusive exocyclic cleavage upon hydrolysis to furnish alpha-substituted carboxylic acid derivatives and the parent oxazinanone in good yield. Asymmetric aldol reactions of a range of aromatic and aliphatic aldehydes with the chlorotitanium enolate of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one proceed with excellent diastereoselectivity. Hydrolysis of the aldol products affords homochiral alpha-methyl-beta-hydroxy-carboxylic acids. |
| first_indexed | 2024-03-06T23:00:42Z |
| format | Journal article |
| id | oxford-uuid:62006303-60c3-45ad-8375-4492a1b1b6df |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T23:00:42Z |
| publishDate | 2006 |
| record_format | dspace |
| spelling | oxford-uuid:62006303-60c3-45ad-8375-4492a1b1b6df2022-03-26T18:03:33ZOxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions.Journal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:62006303-60c3-45ad-8375-4492a1b1b6dfEnglishSymplectic Elements at Oxford2006Davies, SGarner, ARoberts, PSmith, ASweet, MThomson, JHomochiral beta-amino esters (prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one than the corresponding Evans oxazolidin-2-one. A C(4)-iso-propyl stereodirecting group within the oxazinanone conveys higher stereoselectivity than the analogous C(4)-phenyl substituent. gem-Dimethyl substitution at C(6) within the oxazinanone framework facilitates exclusive exocyclic cleavage upon hydrolysis to furnish alpha-substituted carboxylic acid derivatives and the parent oxazinanone in good yield. Asymmetric aldol reactions of a range of aromatic and aliphatic aldehydes with the chlorotitanium enolate of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one proceed with excellent diastereoselectivity. Hydrolysis of the aldol products affords homochiral alpha-methyl-beta-hydroxy-carboxylic acids. |
| spellingShingle | Davies, S Garner, A Roberts, P Smith, A Sweet, M Thomson, J Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title | Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title_full | Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title_fullStr | Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title_full_unstemmed | Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title_short | Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions. |
| title_sort | oxazinanones as chiral auxiliaries synthesis and evaluation in enolate alkylations and aldol reactions |
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