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Selection between Diastereomeric Kinetic vs Thermodynamic Carbonyl Binding Modes Enables Enantioselective Iridium-Catalyzed anti-(α-Aryl)allylation of Aqueous Fluoral Hydrate and Difluoroacetaldehyde Ethyl Hemiacetal
journal contributionposted on 2018-07-18, 20:18 authored by James M. Cabrera, Johannes Tauber, Wandi Zhang, Ming Xiang, Michael J. Krische
Enantioselectivity increases with increasing carbonyl electrophilicity in 2-propanol-mediated reductive couplings of aldehydes with branched aryl-substituted allylic acetates to form products of carbonyl anti-(α-aryl)allylation. This unusual phenomenon is caused by aldehyde coordination to diastereomeric kinetic vs thermodynamic carbonyl binding sites that deliver enantiomeric products. Exploiting this effect, anti-diastereo- and enantioselective (α-aryl)allylations of fluoral hydrate and difluoroacetaldehyde ethyl hemiacetal were developed.
aryl-substituted allylic acetatesDiastereomeric Kinetic vs Thermodynamic Carbonyl Binding Modes Enables Enantioselective Iridium-Catalyzedenantiomeric productsDifluoroacetaldehyde Ethyl Hemiacetal Enantioselectivity increasescarbonyl electrophilicityaldehyde coordinationcarbonyl binding sitesform products2- propanol-mediated reductive couplingsfluoral hydratedifluoroacetaldehyde ethyl hemiacetalAqueous Fluoral Hydrate