title: Direct amination of homoenolates catalyzed by N-heterocyclic carbenes.
abstract: N-Heterocyclic carbenes derived from N-mesityl-N-methyltriazolium salts are effective catalysts for generating homoenolate species from alpha,beta-unsaturated aldehydes. The unique intermediate adds to the electrophilic nitrogen of 1-acyl-2-aryldiazenes, and the resulting activated carbonyl unit undergoes an intramolecular acylation event. This formal [3+2] cycloaddition between alpha,beta-unsaturated aldehydes and acylaryldiazenes, catalyzed by an N-heterocyclic carbene, produces substituted pyrazolidinones in good yields. This new NHC-catalyzed reaction accommodates aromatic and alkyl alpha,beta-unsaturated aldehydes and various aromatic diazenes. A chiral triazolium salt catalyzes the formation of the pyrazolidinone product in moderate yield and good enantioselectivity. The pyrazolidinones can undergo reductive N-N bond cleavage to give beta-amino acid derivatives.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Chan
authors.forename: Karl A
authors.initials: KA
authors.lastname: Scheidt
mesh_terms: D000586:Amination; D002384:Catalysis; D006571:Heterocyclic Compounds / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D006571:Heterocyclic Compounds; D006838:Hydrocarbons; D007659:Ketones; C030011:carbene; D008697:Methane