title: Chiral copper complexes of phosphino sulfenyl ferrocenes as efficient catalysts for enantioselective formal Aza Diels-Alder reactions of N-sulfonyl imines.
abstract: In the presence of a catalytic amount of silver perchlorate, copper(I) bromide complexes of planar chiral 1-phosphino-2-sulfenylferrocenes behave as very efficient chiral Lewis acids catalysts in the formal Aza Diels-Alder reaction of N-arylsulfonyl aldimines with electron-rich dienes (Danishefsky's and related dienes). Mixing of equimolar amounts of the readily available enantiopure ferrocenyl P,S-bidentate ligand and CuBr quantitatively affords the precatalyst Cu complex as an air-stable solid. This catalytic asymmetric procedure has a broad structural scope: aldimines of aromatic, alpha,beta-unsaturated, and even enolizable aliphatic aldehydes have been successfully used. The corresponding 2,3-dihydro-4-pyridones were obtained in good yields (57-90%) and with homogeneously high enantioselectivity (82-97% ee).
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid.
authors.forename: Olga
authors.initials: O
authors.lastname: García Mancheño
authors.forename: Ramón
authors.initials: R
authors.lastname: Gómez Arrayás
authors.forename: Juan C
authors.initials: JC
authors.lastname: Carretero