title: Cyclic ketimines as superior electrophiles for NHC-catalyzed homoenolate additions with broad scope and low catalyst loadings.
abstract: Cyclic sulfonyl imines derived from ketones were identified as stable and readily prepared compounds that serve as superior electrophiles for N-heterocyclic carbene (NHC)-catalyzed annulations with alpha,beta-unsaturated aldehydes to afford highly substituted gamma-lactams. Their superior reactivity and properties are highlighted by the first example of NHC-catalyzed reactions of enals with low catalyst loadings (0.5 mol %) and broad substrate scope encompassing alkyl, aryl, and heteroaromatic substituents. These findings and supporting studies suggest an alternative, ene-like mechanism rather than the catalytic generation of a catalyst-bound homoenolate equivalent.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Rommel
authors.forename: Takeo
authors.initials: T
authors.lastname: Fukuzumi
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Bode
mesh_terms: D000171:Acrolein / Q000031:analogs & derivatives / Q000737:chemistry; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D003500:Cyclization; D007093:Imidazoles / Q000737:chemistry; D007097:Imines / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D007769:Lactams / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D007093:Imidazoles; D007097:Imines; D007659:Ketones; D007769:Lactams; C030011:carbene; D000171:Acrolein; C029899:imidazole; D008697:Methane; C012843:cinnamaldehyde