Enantioselective organocatalytic cyclopropanations. The identification of a new class of iminium catalyst based upon directed electrostatic activation.
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.
Kunz
Roxanne K
RK
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
MacMillan
David W C
DW
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
D000447:Aldehydes; D003521:Cyclopropanes; D007097:Imines; D007211:Indoles