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Issue 15, 1998
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Chiral lithium amide base-mediated rearrangement of bis-protected meso-4,5-dihydroxy cyclohexene oxides: enantioselective synthesis of (4R,5S )- and (4S,5R)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enone

Abstract

The asymmetric synthesis of (4R,5S )- and (4S,5R)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enone are described. Such bis-protected enones are useful intermediates in synthesis, and compounds with (4S,5R)-stereochemistry have previously been prepared from D-(–)-quinic acid. This paper reports the first synthesis of enones with (4R,5S )-stereochemistry. The route to the bis-protected enones involves chiral base-mediated rearrangement of meso-cyclohexene oxides to allylic alcohols followed by PDC oxidation. Two new chiral base reactions are described: rearrangement of a trans-epoxide generates an allylic alcohol of 76% ee (93% yield) whilst that of a cis-epoxide produces an allylic alcohol of 92% ee (38% yield); suggestions for the observed differences in yield and enantioselectivities are proposed.

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Article type: Paper
DOI: 10.1039/A802361A
J. Chem. Soc., Perkin Trans. 1, 1998, 2435-2442

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    Chiral lithium amide base-mediated rearrangement of bis-protected meso-4,5-dihydroxy cyclohexene oxides: enantioselective synthesis of (4R,5S )- and (4S,5R)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enone

    P. O’Brien and P. Poumellec, J. Chem. Soc., Perkin Trans. 1, 1998, 2435
    DOI: 10.1039/A802361A

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