title: Direct organocatalytic asymmetric alpha-sulfenylation of activated C-H bonds in lactones, lactams, and beta-dicarbonyl compounds.
abstract: The application of cinchona alkaloid derivatives as catalysts for enantioselective alpha-sulfenylation of activated C-H bonds in lactones, lactams, and beta-dicarbonyl compounds by different electrophilic sulfur reagents is presented. Optically active products are obtained in good to excellent yields and up to 91 % ee. Furthermore, the diastereoselective reduction of alpha-sulfenylated beta-keto esters to give optically active alpha-sulfenylated beta-hydroxy esters has been studied. A model for the intermediate is presented, in which the protonated cinchona alkaloid interacts with the substrate leading to face-shielding in accordance with the enantioselective alpha-sulfenylation step.
authors: Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark.
authors: Sara
authors: S
authors: Sobhani
authors: Doris
authors: D
authors: Fielenbach
authors: Mauro
authors: M
authors: Marigo
authors: Tobias C
authors: TC
authors: Wabnitz
authors: Karl Anker
authors: KA
authors: Jørgensen
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D007769:Lactams / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008958:Models, Molecular; D013416:Sulfamerazine / Q000737:chemistry*
chemical_list: D007659:Ketones; D007769:Lactams; D007783:Lactones; C012049:sulfaperine; D002244:Carbon; D006859:Hydrogen; D013416:Sulfamerazine