Stereoselective addition of chiral titanium enolates to 5-substituted five-membered oxocarbenium ions
The sterochemical outcome of the addition of chiral titanium enolates to gamma-lactols derived from (S)-glutamic acid were examined. When 5-substituted gamma-lactols were treated with chiral titanium enolates of N-acetyl-, N-propionyl-, N-bromoacetyl- and N-phenylacetyl oxazolidin-2-ones, only two diastereoisomers were obtained, revealing complete facial control by the chiral titanium enolate while the oxocarbenium ion facial discrimination was dependent on the nature of the enolate R³ substituent. After desilylation with aqueous HF/CH3CN, LiBH4 reduction allowed the efficient preparation of the corresponding trans-2,5-disubstituted tetrahydrofuran diols and recovery of the chiral auxiliary.
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| Main Authors: | , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
2008
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532008000300030 |
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