title: Direct and enantioselective organocatalytic alpha-chlorination of aldehydes.
abstract: The first direct enantioselective catalytic alpha-chlorination of aldehydes has been accomplished. The use of enamine catalysis has provided a new organocatalytic strategy for the enantioselective chlorination of aldehydes to generate alpha-chloro aldehydes, an important chiral synthon for chemical and medicinal agent synthesis. The use of imidazolidinone 3 as the asymmetric catalyst has been found to mediate the halogenation of a large variety of aldehyde substrates with the perchlorinated quinone 1 serving as the electrophilic chlorinating reagent. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. The capacity of catalyst 3 to override the inherent bias of resident stereogenicity in the chlorination of enantiopure beta-chiral aldehydes is also described. Catalyst quantities of 5 mol % were generally employed in this study.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Brochu
authors.forename: Sean P
authors.initials: SP
authors.lastname: Brown
authors.forename: David W C
authors.initials: DW
authors.lastname: MacMillan