title: Rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to alpha,beta-unsaturated amides.
abstract: The conjugate addition of arylboronic acids to alpha,beta-unsaturated amides was carried out in the presence of a chiral rhodium catalyst and an aqueous base. The catalyst prepared in situ from Rh(acac)(CH(2)=CH(2))(2) and (S)-binap provided (R)-N-benzyl-3-phenylbutanamide with 93% ee in the addition of phenylboronic acid to N-benzyl crotonamide. The reaction suffered from incomplete conversion resulting in moderate yields, but addition of an aqueous base, such as K(2)CO(3) (10-50 mol%) was found to be highly effective to improve the chemical yields. The role of the base giving a RhOH species active for transmetalation with arylboronic acids was discussed.
authors.affiliation: Division of Molecular Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Sakuma
authors.forename: N
authors.initials: N
authors.lastname: Miyaura