Helvetica Chimica Acta · 1999 · 62 citations · 0 references
Natural SciencesChemistryCatalysisOrganic ChemistryOrganometallic ChemistryCatalyst PreparationCatalytic MaterialsCatalytic MechanismsHeterocyclic ChemistryOrganic SynthesisReaction MechanismsCatalyst Structure - Activity RelationshipsCatalytic Reaction MechanismsCis-trans IsomerismCyclopropanation ReactionsEnantioselective CatalysisEnantioselectivity
Olefins undergo cyclopropanation with diphenylsulfonium (ethoxycarbonyl)methylide (=diphenylsulfonium 2-ethoxy-2-oxoethylide; 3a) in the presence of chiral CuI or RhII catalysts. trans/cis Ratios and ee's of the cyclopropanes 6 obtained with this ylide in the presence of a chiral CuI catalyst 7 are identical with those obtained with ethyl diazoacetate (4). In the case of catalysis with RhII, the trans/cis ratios of the cyclopropanes as well as the enantioselectivity change slightly upon going from the ylide 3a to diazoacetate 4.