title: Catalytic asymmetric protonation of chiral calcium enolates via 1,4-addition of malonates.
abstract: Catalytic asymmetric protonation of chiral calcium enolates was performed. Chiral calcium enolates, prepared in situ from imides and malonates via 1,4-addition in the presence of catalytic amounts of Ca(OEt)(2), Ph-PyBox, and achiral phenol, were smoothly protonated to afford adducts bearing tertiary asymmetric carbons in high yields with high enantioselectivities. The adducts were readily converted to optically active 2-substituted 1,5-dicarboxylic acid derivatives.
authors.affiliation: Department of Chemistry, School of Science and Graduate School of Pharmaceutical Sciences, The University of Tokyo, The HFRE Division, ERATO, Japan Science and Technology Agency (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Thomas
authors.initials: T
authors.lastname: Poisson
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Shū
authors.initials: S
authors.lastname: Kobayashi
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D002384:Catalysis; D008024:Ligands; D008314:Malonates / Q000737:chemistry*; D011522:Protons; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D008024:Ligands; D008314:Malonates; D011522:Protons; D002118:Calcium