title: Size of gold nanoparticles driving selective amide synthesis through aerobic condensation of aldehydes and amines.
abstract: Metal nanoparticles (NPs) have attracted much attention in many fields due to their intrinsic characteristics. It is generally accepted that smaller NPs (1.5-3 nm) are more active than larger NPs, and reverse cases are very rare. We report here the direct aerobic oxidative amide synthesis from aldehydes and amines catalyzed by polymer-incarcerated gold (Au) NPs. A unique correlation between imine/amide selectivity and size of NPs was discovered; Au-NPs of medium size (4.5-11 nm) were found to be optimal. High yields were obtained with a broad range of substrates, including primary amines. Au-NPs of medium size could be recovered and reused several times without loss of activity, and they showed good activity and selectivity in amide formation from alcohols and amines.
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan).
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Miyamura
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan).
authors.forename: Hyemin
authors.initials: H
authors.lastname: Min
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan).
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Soulé
authors.affiliation: Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan). shu_kobayashi@chem.s.u-tokyo.ac.jp.
authors.forename: Shū
authors.initials: S
authors.lastname: Kobayashi
keywords: aerobic oxidation; amide synthesis; gold nanoparticles; heterogeneous catalysis