title: Rhodium-catalyzed ring-opening reactions of N-boc-azabenzonorbornadienes with amine nucleophiles.
abstract: In the presence of a rhodium catalyst (5 mol %) generated in situ from [Rh(cod)Cl](2) and (S,S')-(R,R')-C(2)-ferriphos (4a), the asymmetric ring-opening reaction of azabenzonorbornadienes (1a-m) with various aliphatic and aromatic amines (2a-l) proceeded with high enantioselectivity (up to >99% ee) to give the corresponding 1,2-diamine derivatives 3 in high yields. In the specific case of pyrrolidine as nucleophile, Et(3)NHCl was necessary as an additive for good reactivity and enantioselectivity. Additionally, a practical protocol was developed for the ring-opening of 1a with volatile amines at elevated temperatures and standard pressure, using R(2)NH(2)I and i-Pr(2)NEt. The experimental results showed that the nature of the chiral ligand has the significant impact on the reactivity of the catalyst and the use of excess amount (2.2 eq to Rh) of the chiral ligand plays an important role to improve the enantioselectivity in the present asymmetric reaction.
authors.affiliation: Davenport Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5H 3H6.
authors.forename: Yong-hwan
authors.initials: YH
authors.lastname: Cho
authors.forename: Valentin
authors.initials: V
authors.lastname: Zunic
authors.forename: Hisanori
authors.initials: H
authors.lastname: Senboku
authors.forename: Madeline
authors.initials: M
authors.lastname: Olsen
authors.forename: Mark
authors.initials: M
authors.lastname: Lautens
mesh_terms: D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D018360:Crystallography, X-Ray; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000588:Amines; D012238:Rhodium