title: Pyridylidene-Mediated Dihydrogen Activation Coupled with Catalytic Imine Reduction.
abstract: In recent years, dihydrogen activation at non-metallic centers has received increasing attention. A system in which dihydrogen is trapped by a pyridylidene intermediate that is generated from a pyridinium salt and a base is now reported. The dihydropyridine formed in this process can act as reducing agent towards organic electrophiles. By coupling the hydrogen-activation step with subsequent hydride transfer from the dihydropyridine to an imine, a catalytic process was established. Treatment of the N-phenylimine of phenyl trifluoromethyl ketone with 5-20 mol% of N-mesityl-3,5-bis(2,6-dimethylphenyl)pyridinium triflate and 0.3-1.0 equivalents of LiN(SiMe3)2 under 50 bar of hydrogen gas resulted in high conversion into the corresponding amine.
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland).
authors.forename: Johanna
authors.initials: J
authors.lastname: Auth
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland).
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Padevet
authors.affiliation: Department of Organic Chemistry, Universidad Autónoma de Madrid c/Fco. Tomás y Valiente 7, Cantoblanco 28049, Madrid (Spain). pablo.mauleon@uam.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Mauleón
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel (Switzerland). andreas.pfaltz@unibas.ch.
authors.forename: Andreas
authors.initials: A
authors.lastname: Pfaltz
keywords: NADH analogues; catalytic hydrogenation; dihydrogen activation; pyridinium salts; pyridylidenes