- AN ASYMMETRIC SYNTHESIS OF 4,4- AND 6,6-DIALKYLCYCLOHEXENONES AND 4,4- AND 5,5-DIALKYLCYCLOPENTENONES. APPLICATION TO THE TOTAL SYNTHESIS OF (-)-SILPHIPERFOL-6-ENE
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Chiral amino alcohols have been transformed into bicyclic lactams 1 and 6 which, after metalation and alkylation, gave high diastereomeric ratios of 2,2-dialkyl quaternaly products, 29 and 12, respectively.Addition of organolithium reagents to the carbonyl of these lactams, followed by acidic cleavage, leads to enantiomerically pure cyclohex-2-enones and cyclopent-2-enones.This process was also applied to a key, chiral cyclopentenone 39, which was used by Curran, in racemic form, to prepare the angular triquinane, silphiperfol-6-ene.The total asymmetric synthesis was carried out in 6.6percent yield over nine steps.
- Meyers, A. I.,Lefker, Bruce A.
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p. 5663 - 5676
(2007/10/02)
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- An Asymmetric Synthesis of Chiral 4,4-Disubstituted Cyclohexenones in High Enantiomeric Purity
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An efficient approach to the title compounds in > 95percent ee has been accomplished by metalation and alkylation of chiral bicyclic lactams derived from δ-keto acids and (1S,2S)-2-amino-1-phenyl-1,3-propanediol.
- Meyers, A. I.,Lefker, Bruce A.,Wanner, Klaus Th.,Aitken, R. Alan
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p. 1936 - 1938
(2007/10/02)
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