Development of a new carbon-carbon bond forming reaction. New organic chemistry of sulfur dioxide. Asymmetric four-component synthesis of polyfunctional sulfones
At low temperature 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or Bronstedt acid and generate zwitterionic intermediates that can be quenched by enoxysilanes. The resulting beta,gamma -unsaturated silyl sulfinates can be desilylated and reacted with methyl iodide to provide polyfunctional sulfones. Exploratory studies of this four-component synthesis of sulfones are reported. Enantiomerically pure derivatives containing up to three new stereogenic centers can be obtained using enantiomerically pure (EE)-1-alkoxy-2-methylpenta-1,3-dienes derived from (alpha -methyl benzyl alcohols, including the Greene's chiral auxiliary. The stereochemistry of the reactions is consistent with a mechanism involving the suprafacial hetero-Diels-Alder addition of sulfur dioxide to the 1-alkoxy-1,3-dienes that are rapidly ionized into zwitterionic intermediates.
Keywords: Hetero-diels-alder ; allylic sulfinic acids ; homocheletropic additions ; stereoselective synthesis ; polypropionate fragments ; cheletropic ; additions ; methyl sulfones ; regioselectivity ; cycloaddition ; derivatives
Univ Lausanne, Chim Sect, BCH, CH-1015 Lausanne, Switzerland. Univ Lausanne, Inst Cristallog, BSP, CH-1015 Lausanne, Switzerland.
Record created on 2005-11-09, modified on 2016-08-08