title: Improved asymmetric S(N)Ar reaction of beta-dicarbonyl compounds catalyzed by quaternary ammonium salts derived from cinchona alkaloids.
abstract: The scope and limitation of the asymmetric nucleophilic aromatic substitution reaction of alpha-substituted 1,3-dicarbonyl compounds and activated aromatic systems catalyzed by N-benzyl-O-benzoylcinchoninium or cinchonidinium salts are presented. Several novel O-benzoylcinchona alkaloid derived salts have been prepared and evaluated as catalysts in this reaction, which can proceed with enantioselectivites up to 96% ee. Various 1,3-dicarbonyl compounds and activated aromatic systems are evaluated for the aromatic nucleophilic substitution reaction, and it has been found that the yield and enantioselectivity are very dependent on the substrate and reagent. The scope of the functionalization of the products to, e.g., spiro-oxoindole, a ring-opening reaction of 1,3 alpha,alpha-disubstituted dicarbonyl compounds with several nucleophiles, and the diastereoselective reduction of the keto functionality in the optically active S(N)Ar product are reported.
authors.affiliation: Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Sara
authors.initials: S
authors.lastname: Kobbelgaard
authors.forename: Marco
authors.initials: M
authors.lastname: Bella
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen
mesh_terms: D002384:Catalysis; D002930:Cinchona Alkaloids / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D002930:Cinchona Alkaloids; D007659:Ketones; D000644:Quaternary Ammonium Compounds