title: Chiral calcium-BINOL phosphate catalyzed diastereo- and enantioselective synthesis of syn-1,2-disubstituted 1,2-diamines: scope and mechanistic studies.
abstract: A highly enantioselective, chiral, Lewis acid calcium-bis(phosphate) complex, Ca[3 a]n, which catalyzes the electrophilic amination of enamides with azodicarboxylate derivatives 2 to provide versatile chiral 1,2-hydrazinoimines 4 is disclosed. The reaction gives an easy entry to optically active syn-1,2-disubstituted 1,2-diamines 6 in high yields with excellent enantioselectivities, after a one-pot reduction of the intermediate 1,2-hydrazinoimines 4. The geometry and nature of the N-substituent of the enamide affect dramatically both the reactivity and the enantioselectivity. Although the calcium-bis(phosphate) complex was a uniquely effective catalyst, the exact nature of the active catalytic species remains unclear. NMR spectroscopy and MS analysis of the various calcium complexes Ca[3]n reveals that the catalysts exist in various oligomer forms. The present mechanistic study, which includes nonlinear effects and kinetic measurements, constitutes a first step in understanding these calcium-bis(phosphate) complex catalysts. DFT calculations were carried out to explore the mechanism and the origin of the enantioselectivity with the Ca[3]n catalysts.
authors.affiliation: Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles CNRS, LabEx CHARM3AT, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex (France), Fax: (+33) 1-6907-7247.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lalli
authors.forename: Audrey
authors.initials: A
authors.lastname: Dumoulin
authors.forename: Clément
authors.initials: C
authors.lastname: Lebée
authors.forename: Fleur
authors.initials: F
authors.lastname: Drouet
authors.forename: Vincent
authors.initials: V
authors.lastname: Guérineau
authors.forename: David
authors.initials: D
authors.lastname: Touboul
authors.forename: Vincent
authors.initials: V
authors.lastname: Gandon
authors.forename: Jieping
authors.initials: J
authors.lastname: Zhu
authors.forename: Géraldine
authors.initials: G
authors.lastname: Masson
mesh_terms: D000586:Amination; D002130:Calcium Phosphates / Q000737:chemistry*; D002384:Catalysis; D003959:Diamines / Q000138:chemical synthesis*; D008958:Models, Molecular; D009284:Naphthols / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C406944:BINOL, naphthol; D002130:Calcium Phosphates; D003959:Diamines; D009284:Naphthols; C020243:calcium phosphate
keywords: amination; calcium; diamines; enamides; nonlinear effects