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Synlett 1990; 1990(5): 282-284
DOI: 10.1055/s-1990-21066
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Epoxide Ring Opening by Dianions Derived from β-Ketosulphones. Synthetic Studies on the 7-Hydroxy-4-oxopropenoate System and Medium-Ring Lactones

Barry Lygo* , Norval O'Connor
  • *Department of Chemistry and Applied Chemistry, University of Salford, Salford, M5 4WT, England
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Publication Date:
08 March 2002 (online)

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The nucleophilic ring opening of an epoxide by the dianion derived from a β-ketosulphone is examined. Alkylation of the anion derived from the β-ketosulphone product with ethyl bromoacetate, followed by elimination of sulphinic acid with 1,8-diazabicyclo[5.4.0]undec-7-ene then leads to trans-7-hydroxy-4-oxopropenoates. Utility of this approach to the preparation of natural product systems is illustrated by a formal synthesis of (±)-pyrenophorin. Preparation of the β-ketosulphone intermediates via reaction of the α,α-dilithiodianion derived from phenyl methyl sulphone with various lactones is also examined. This approach is extended to the preparation of 8-, 9-, and 10-ring lactones possessing cis-7-, -8-, and -9-hydroxy-4-oxopropenoate moieties, respectively, by the intramolecular alkylation of β-ketosulphones containing a bromoacetoxy group.

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