Organocatalytic asymmetric synthesis of Si-stereogenic silacycles
Jung Tae Han, Nobuya Tsuji, Hui Zhou, Markus Leutzsch, Benjamin List
Abstract
A strong and confined Brønsted acid catalyzed enantioselective cyclization of bis(methallyl)silanes provides enantioenriched Si-stereogenic silacycles. High enantioselectivities of up to 96.5:3.5 er were obtained for a range of bis(methallyl)silanes. NMR and ESI-MS studies reveal that the formation of a covalent adduct irreversibly inhibits turnover. Remarkably, we found that acetic acid as an additive promotes the collapse of this adduct, enabling full turnover. Experimental investigation and density functional theory (DFT) calculations were conducted to elucidate the origin of this phenomenon and the observed enantioselectivity.
Topics & Concepts
StereocenterSilanesAdductEnantioselective synthesisChemistryAcetic acidDensity functional theoryOrganocatalysisCovalent bondCatalysisStereochemistryOrganic chemistryComputational chemistrySilaneOrganoboron and organosilicon chemistrySynthetic Organic Chemistry MethodsCyclopropane Reaction Mechanisms