title: An imidazoline-aminophenol (IAP) nickel catalyst: structure and catalytic activity in the enantioselective 1,4-addition of 3'-indolyl-3-oxindoles to nitroethylene.
abstract: The structure of a nickel complex of imidazoline-aminophenol (IAP) prepared from IAP with Ni(OAc)2 was elucidated as cis-bis(imidazolineaminophenoxide) [Ni(IAP)2]. The [Ni(IAP)2] complex smoothly promoted catalytic asymmetric 1,4-addition of 3'-indolyl-3-oxindole to nitroethylene to provide chiral mixed 3,3'-bisindoles with high enantioselectivities. Mechanistic studies using ESI-MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)2] to generate the Ni-enolate of 3'-indolyl-3-oxindole. From the optically active 3,3'-mixed indole adduct, biologically important 3'-indolyl-3-pyrrolidinoindoline was successfully synthesized in a three-step reaction sequence.
authors: Department of Chemistry, Graduate School of Science, Chiba University, Inage, Chiba 263-8522 (Japan), Fax: (+81) 43-290-2889.
authors: Atsuko
authors: A
authors: Awata
authors: Makiko
authors: M
authors: Wasai
authors: Hyuma
authors: H
authors: Masu
authors: Sayaka
authors: S
authors: Kado
authors: Takayoshi
authors: T
authors: Arai
keywords: asymmetric catalysis; indole 1,4-addition; nickel; tridentate ligands