Phosphine Catalyzed α-Arylation of Enones and Enals Using Hypervalent Bismuth Reagents: Regiospecific Enolate Arylation via Nucleophilic Catalysis
摘要:
Exposure of enones and enals to 20 mol % tributylphosphine in the presence of triarylbismuth(V) dichlorides results in regiospecific aryl transfer to the alpha-position of the enone or enal pronucleophile. These results represent the first examples of enolate arylation under the conditions of nucleophilic catalysis.
A Conia‐Ene‐Type Cyclization under Basic Conditions Enables an Efficient Synthesis of (−)‐Lycoposerramine R
作者:Felix W. W. Hartrampf、Takayuki Furukawa、Dirk Trauner
DOI:10.1002/anie.201610021
日期:2017.1.16
An enantioselective total synthesis of the Lycopodium alkaloid lycoposerramine R is presented. It relies on a base‐mediated cyclization that resembles the Conia‐ene reaction of ynones and gold‐catalyzed variants thereof. Thus, hydrindanones and other functionalized ring systems bearing an exocyclic alkene can be rapidly accessed at room temperature without noble metal catalysis or substrate preactivation
An expeditious synthesis of α-aryl- and α-alkynylcyclohexenones is described and illustrated by palladium-catalyzed cross-coupling reaction of cyclic α-iodoenones with potassium aryl-trifluoroborate salts. This procedure offers easy access to α-arylated and alkynylated cyclohexenones functionalized with electrondonor and -acceptor substituents in good yields.
Dynamic Kinetic Resolution of γ-Substituted Cyclic β-Ketoesters via Asymmetric Hydrogenation: Constructing Chiral Cyclic β-Hydroxyesters with Three Contiguous Stereocenters
An efficient asymmetric hydrogenation of racemic γ-substituted cyclic β-ketoesters via dynamic kineticresolution to provide chiral cyclic β-hydroxy esters with threecontiguousstereocenters is reported. Using a chiral spiro iridium catalyst (R)-5 (Ir-SpiroSAP), a series of racemic γ-aryl/alkyl substituted cyclic β-ketoesters were hydrogenated to the corresponding chiral cyclic β-hydroxy esters in
Phosphine Catalyzed α-Arylation of Enones and Enals Using Hypervalent Bismuth Reagents: Regiospecific Enolate Arylation via Nucleophilic Catalysis
作者:Phillip K. Koech、Michael J. Krische
DOI:10.1021/ja048987i
日期:2004.5.1
Exposure of enones and enals to 20 mol % tributylphosphine in the presence of triarylbismuth(V) dichlorides results in regiospecific aryl transfer to the alpha-position of the enone or enal pronucleophile. These results represent the first examples of enolate arylation under the conditions of nucleophilic catalysis.
The first palladium-catalyzedasymmetric allylic trifluoromethylation is disclosed. The methodology evokes a fundamental principle by which the synergistic interplay of a leaving group and its subsequent activation of the nucleophilic trifluoromethyl group enabled the reaction. Allyl fluorides have been shown to be superior precursors for generation of π-allyl complexes, which lead to trifluoromethylated