title: Enantioselective organocatalytic cyclopropanations. The identification of a new class of iminium catalyst based upon directed electrostatic activation.
abstract: A new method for enantioselective organocatalytic cyclopropanation is described. This study outlines the identification of a new class of iminium catalyst based on the concept of directed electrostatic activation (DEA). This novel organocatalytic mechanism exploits dual activation of ylide and enal substrates through a proposed electrostatic activation and stereodirected protocol. Formation of trisubstituted cyclopropanes with high levels of enantio- and diastereoinduction is accomplished for a variety of alpha,beta-unsaturated aldehydes and sulfonium ylides. In addition, mechanistic studies have found that this cyclopropanation reaction exhibits enantioselectivity and reactivity profiles that are in accord with the proposed DEA step.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
authors.forename: Roxanne K
authors.initials: RK
authors.lastname: Kunz
authors.forename: David W C
authors.initials: DW
authors.lastname: MacMillan
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D007097:Imines / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D008958:Models, Molecular; D055672:Static Electricity; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; D003521:Cyclopropanes; D007097:Imines; D007211:Indoles