6533b7d9fe1ef96bd126ca6c
RESEARCH PRODUCT
Asymmetric Homoaldol Reactions with Cyclohex-2-enylN,N-Diisopropylcarbamate: Kinetic Resolution, Elucidation of the Stereochemical Course and Applications in the Synthesis of Hexahydroisobenzofuran-4-(1H)-ones
Dieter HoppeRoland FröhlichJochen BeckerKirsi Salorinnesubject
Electrophilic substitutionStereospecificityDeprotonationChemistryStereochemistryOrganic ChemistryElectrophileEnantioselective synthesischemistry.chemical_elementLithiumPhysical and Theoretical ChemistryTinKinetic resolutiondescription
Enantio-enriched cyclohex-2-enyl N,N-diisopropylcarbamate (5) is stereospecifically deprotonated by sec-butyllithium/(–)-sparteine (9) to form the configurationally stable lithium complex 7·9. A kinetic resolution of rac-5 by n-butyllithium/(–)-sparteine (9) yielded (R)-5 with up to 99 % ee. Electrophilic substitution with tin electrophiles proceeds in a anti-SE′ fashion as shown by chemical correlations. The synthesized allylstannanes 10 undergo a highly stereospecific TiCl4-mediated homoaldol reaction with various aldehydes, yielding syn-configured homoaldol products 12. These were transferred into all-cis-configured hexahydroisobenzofuran-4(1H)-ones 22 by BF3·OEt2-mediated reactions with aldehydes. The configurations of several products were determined by X-ray structure analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
year | journal | country | edition | language |
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2007-07-01 | European Journal of Organic Chemistry |