Both enantiomers of the trans stereoisomer of magnolione 4 have been prepared by asymmetric Michael addition of ethyl acetoacetate to 2-pentylcyclopentenone, followed by hydrolysis/decarboxylation. The Michael reaction occurs under solid/liquid phase transfer catalysis in the presence of N-methylanthracenylquininium (or quinidinium) chloride. Enantiomeric excesses up to 76% are obtained. The trans structure of the compounds has been fully established by a careful NMR analysis, while the absolute configuration has been assigned as (2S,3S) for (+)-4 by the analysis of the CD spectrum. © 2004 Elsevier Ltd. All rights reserved.
Enantioselective synthesis and absolute stereochemistry of both enantiomers of trans- magnolione, a fragrance structurally related to trans-methyl jasmonate
SCAFATO, Patrizia;CASARINI, Daniele;ROSINI, Carlo
2004-01-01
Abstract
Both enantiomers of the trans stereoisomer of magnolione 4 have been prepared by asymmetric Michael addition of ethyl acetoacetate to 2-pentylcyclopentenone, followed by hydrolysis/decarboxylation. The Michael reaction occurs under solid/liquid phase transfer catalysis in the presence of N-methylanthracenylquininium (or quinidinium) chloride. Enantiomeric excesses up to 76% are obtained. The trans structure of the compounds has been fully established by a careful NMR analysis, while the absolute configuration has been assigned as (2S,3S) for (+)-4 by the analysis of the CD spectrum. © 2004 Elsevier Ltd. All rights reserved.File in questo prodotto:
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