title: [(IPent)PdCl2(morpholine)]: a readily activated precatalyst for room-temperature, additive-free carbon-sulfur coupling.
abstract: A series of new, easily activated NHC-Pd(II) precatalysts featuring a trans-oriented morpholine ligand were prepared and evaluated for activity in carbon-sulfur cross-coupling chemistry. [(IPent)PdCl2(morpholine)] (IPent=1,3-bis(2,6-di(3-pentyl)phenyl)imidazol-2-ylidene) was identified as the most active precatalyst and was shown to effectively couple a wide variety of deactivated aryl halides with both aryl and alkyl thiols at or near ambient temperature, without the need for additives, external activators, or pre-activation steps. Mechanistic studies revealed that, in contrast to other common NHC-Pd(II) precatalysts, these complexes are rapidly reduced to the active NHC-Pd(0) species at ambient temperature in the presence of KOtBu, thus avoiding the formation of deleterious off-cycle Pd(II)-thiolate resting states.
authors.affiliation: Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3 (Canada).
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Farmer
authors.forename: Matthew
authors.initials: M
authors.lastname: Pompeo
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Lough
authors.forename: Michael G
authors.initials: MG
authors.lastname: Organ
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D015394:Molecular Structure; D009025:Morpholines / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry; D013696:Temperature
chemical_list: C000599920:(IPent)PdCl2(morpholine); D056831:Coordination Complexes; D009025:Morpholines; D013455:Sulfur; D002244:Carbon; C037574:morpholine
keywords: N-heterocyclic carbenes; PEPPSI; homogeneous catalysis; palladium; sulfination