A sulfinyl-directed asymmetric [5C + 2C] intramolecular acetoxypyranone-alkene cycloaddition.
[reaction: see text] Introduction of a homochiral p-tolylsulfinyl group at the trans terminal position of an alkene induces a total diastereodifferentiation in the intramolecular cycloaddition of the latter to 3-oxidopyrylium ylide precursors. The cycloadducts can be readily desulfinylated to afford enantiomerically pure oxa-bridged bicyclo[5.3.0]decane ring systems. Theoretical calculations confirm that diastereoselectivity stems from the conformational preferences of the alkenylsulfoxide unit in the transition state of the reaction.
López
Fernando
F
Departamento de Química Orgánica y Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Castedo
Luis
L
Mascareñas
José L
JL