title: Rhodium-catalyzed 1,4-addition of lithium 2-furyltriolborates to unsaturated ketones and esters for enantioselective synthesis of γ-oxo-carboxylic acids by oxidation of the furyl ring with ozone.
abstract: Rhodium-catalyzed 1,4-addition of lithium 5-methyl-2-furyltriolborate ([ArB(OCH(2))(3)CCH(3)]Li, Ar = 5-methyl-2-furyl) to unsaturated ketones to give β-furyl ketones was followed by ozonolysis of the furyl ring for enantioselective synthesis of γ-oxo-carboxylic acids. [Rh(nbd)(2)]BF(4) (nbd = 2,5-norbornadiene) chelated with 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (binap) or 2,3-bis(diphenylphosphino)butane (chiraphos) gave high yields and high selectivities in a range of 91-99% ee at 30 °C in a basic dioxane/water solution. The corresponding reaction of unsaturated esters, such as methyl crotonate, had strong resistance under analogous conditions, but the 1,4-adduct was obtained in 70% yield and with 94% ee when more electron-deficient phenyl crotonate was used as the substrate.
authors.affiliation: Division of Chemical Process Engineering, Graduate School of Engineering, Hokkaido University, N13, W8, Sapporo 060-8628, Japan.
authors.forename: Xiao-Qiang
authors.initials: XQ
authors.lastname: Yu
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Shirai
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Norio
authors.initials: N
authors.lastname: Miyaura
mesh_terms: D001881:Borates / Q000138:chemical synthesis / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D004952:Esters; D007659:Ketones / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001881:Borates; D002264:Carboxylic Acids; D004952:Esters; D007659:Ketones; D010126:Ozone; D008094:Lithium; D012238:Rhodium