Halogen‐Bridged Methylnaphthyl Palladium Dimers as Versatile Catalyst Precursors in Coupling Reactions

Abstract

Halogen-bridged methylnaphthyl (MeNAP) palladium dimers are presented as multipurpose Pd-precursors, ideally suited for catalytic method development and preparative organic synthesis.B ys imply mixing with phosphine or carbene ligands,t hey are in situ converted into well-defined monoligated complexes.T heir catalytic performance was benchmarked against state-of-the-art systems in challenging Buchwald-Hartwig, Heck, Suzuki and Negishi couplings,and ketone arylations.T heir use enabled record-setting activities, beyond those achievable by optimization of the ligand alone. The MeNAP catalysts permit syntheses of tetra-ortho-substituted arenes and bulky anilines in near-quantitative yields at room temperature,a llowm ono-arylations of small ketones, and enable so far elusive cross-couplings of secondary alkyl boronic acids with aryl chlorides.

Formation of exceptional monomeric YPhos–PdCl2complexes with high activities in coupling reactions

“…Here, the design has focused on optimizing the generation of the LPd(0) species, leading to the development of a series of anionic coligands that facilitate the reduction process and minimize catalyst deactivation through formation of inactive metal species. Successfully applied complexes include η 3 -allyl systems such as allyl, crotyl or cinamyl (A), 11,12 indenyl (B) 13 or methylnaphthyl C 14 complexes as well as palladacycles 15 above all based on the 2-aminobiphenyl structure (D, Figure 1). 16 Also oxidative addition complexes of type [LPd(Ar)Cl]x (x = 0 or 1) have been used as "on-cycle" precatalysts, as was first described by Shaughenessy in 2017.…”

Solvent‐Free Synthesis of Core‐Functionalised Naphthalene Diimides by Using a Vibratory Ball Mill: Suzuki, Sonogashira and Buchwald–Hartwig Reactions

“…Currently, there are three solution‐state studies which furnish aminated c‐NDIs in modest yields (ca. 22–55 %) [28a,47] . Each reports their synthesis using similar Buchwald‐Hartwig type conditions: long reaction times (typically >12 h) with an inert solvent, a strong base such as sodium tert ‐butoxide, a palladium source, and a diaryl secondary amine as the coupling partner.…”

Important Role of NH-Carbazole in Aryl Amination Reactions Catalyzed by 2-Aminobiphenyl Palladacycles

“…Such ligands are actively involved in the activation step, but they can also participate in additional off-cycle reactions, resulting in a decrease in catalytic activity. Evidence of this is the catalyst deactivation pathway found for [Pd­(L)­Cl­(allyl)] (L = NHC, phosphine) precatalysts by formation of a Pd­(I) dimer stabilized by a bridging allyl ligand. − …”