title: Bis-N-heterocyclic Carbene Aminopincer Ligands Enable High Activity in Ru-Catalyzed Ester Hydrogenation.
abstract: Bis-N-heterocyclic carbene (NHC) aminopincer ligands were successfully applied for the first time in the catalytic hydrogenation of esters. We have isolated and characterized a well-defined catalyst precursor as a dimeric [Ru2(L)2Cl3]PF6 complex and studied its reactivity and catalytic performance. Remarkable initial activities up to 283,000 h(-1) were achieved in the hydrogenation of ethyl hexanoate at only 12.5 ppm Ru loading. A wide range of aliphatic and aromatic esters can be converted with this catalyst to corresponding alcohols in near quantitative yields. The described synthetic protocol makes use of air-stable reagents available in multigram quantities, rendering the bis-NHC ligands an attractive alternative to the conventional phosphine-based systems.
authors.forename: Georgy A
authors.initials: GA
authors.lastname: Filonenko
authors.affiliation: §DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, The Netherlands.
authors.forename: Mae Joanne B
authors.initials: MJ
authors.lastname: Aguila
authors.forename: Erik N
authors.initials: EN
authors.lastname: Schulpen
authors.forename: Robbert
authors.initials: R
authors.lastname: van Putten
authors.affiliation: ∥Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany.
authors.forename: Jelena
authors.initials: J
authors.lastname: Wiecko
authors.affiliation: ∥Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36, D-14195 Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Müller
authors.affiliation: §DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, The Netherlands.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lefort
authors.forename: Emiel J M
authors.initials: EJ
authors.lastname: Hensen
authors.forename: Evgeny A
authors.initials: EA
authors.lastname: Pidko