title: Tetraalkylammonium Salts as Hydrogen-Bonding Catalysts.
abstract: Although the hydrogen-bonding ability of the α hydrogen atoms on tetraalkylammonium salts is often discussed with respect to phase-transfer catalysts, catalysis that utilizes the hydrogen-bond-donor properties of tetraalkylammonium salts remains unknown. Herein, we demonstrate hydrogen-bonding catalysis with newly designed tetraalkylammonium salt catalysts in Mannich-type reactions. The structure and the hydrogen-bonding ability of the new ammonium salts were investigated by X-ray diffraction analysis and NMR titration studies.
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry. seijishirakawa@nagasaki-u.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Shirakawa
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry.
authors.forename: Shiyao
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry.
authors.forename: Shiho
authors.initials: S
authors.lastname: Kaneko
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kumatabara
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry.
authors.forename: Airi
authors.initials: A
authors.lastname: Fukuda
authors.affiliation: Department of Environmental Science, Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan) http://seijishirakawa.wix.com/greenchemistry.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Omagari
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502 (Japan). maruoka@kuchem.kyoto-u.ac.jp.
authors.forename: Keiji
authors.initials: K
authors.lastname: Maruoka
keywords: acidity; hydrogen bonds; hydrogen-bonding catalysts; organocatalysis; tetraalkylammonium salts