title: Enantioselective thiourea-catalyzed additions to oxocarbenium ions.
abstract: Asymmetric, catalytic reactions of oxocarbenium ions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbenium ion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities, with the optimal structure being derived from enantioenriched 2-arylpyrrolidine derivatives.
authors.affiliation: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Reisman
authors.forename: Abigail G
authors.initials: AG
authors.lastname: Doyle
authors.forename: Eric N
authors.initials: EN
authors.lastname: Jacobsen
mesh_terms: D000080:Acetals / Q000737:chemistry*; D002384:Catalysis; D002839:Chromans / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism; D013890:Thiourea / Q000737:chemistry*
chemical_list: D000080:Acetals; D002839:Chromans; D013890:Thiourea