title: An Insoluble Copper(II) Acetylacetonate-Chiral Bipyridine Complex that Catalyzes Asymmetric Silyl Conjugate Addition in Water.
abstract: Acicular purplish crystals were obtained from Cu(acac)2 and a chiral bipyridine ligand. Although the crystals were not soluble, they nevertheless catalyzed asymmetric silyl conjugate addition of lipophilic substrates in water. Indeed, the reactions proceeded efficiently only in water; they did not proceed well either in organic solvents or in mixed water/organic solvents in which the catalyst/substrates were soluble. This is in pronounced contrast to conventional organic reactions wherein the catalyst/substrates tend to be in solution. Several advantages of the chiral Cu(II) catalysis in water over previously reported catalyst systems have been demonstrated. Water is expected to play a prominent role in constructing and stabilizing sterically confined transition states and accelerating subsequent protonation to achieve high yields and enantioselectivities.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Kitanosono
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Pengyu
authors.initials: P
authors.lastname: Xu
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo , Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Shū
authors.initials: S
authors.lastname: Kobayashi