title: Calcium-catalyzed asymmetric synthesis of 3-tetrasubstituted oxindoles: efficient construction of adjacent quaternary and tertiary chiral centers.
abstract: Chiral Ca-catalyzed asymmetric addition reactions of 3-substituted oxindoles with N-Boc-imines afford 3-tetrasubstituted oxindole derivatives bearing adjacent quaternary and tertiary chiral centers, which are key structures for biological activities. Ubiquitous and nontoxic Ca catalysts (1-10 mol %) work well in this reaction, and high yields (up to 99%) and selectivities (up to >99% ee) of the products with wide substrate scope have been attained. The structures of the chiral Ca catalysts and intermediary Ca enolates are also discussed.
authors: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Shota
authors: S
authors: Shimizu
authors: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Tetsu
authors: T
authors: Tsubogo
authors: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Pengyu
authors: P
authors: Xu
authors: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Shū
authors: S
authors: Kobayashi
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002384:Catalysis; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D000078183:Oxindoles; D011789:Quantum Theory
chemical_list: D007211:Indoles; D009942:Organometallic Compounds; D000078183:Oxindoles; C022960:2-oxindole; D002118:Calcium