Palladium-catalyzed denitrogenative Hiyama cross-coupling with arylhydrazines under air

Palladium-Catalyzed Hiyama Cross-Coupling of Heterocyclic Phosphonium Salts with Arylsilanes

We report herein the palladium-catalyzed Hiyama cross-coupling of heterocyclic phosphonium salts with diverse (hetero)arylsilanes through C-P bond cleavage, providing an alternative approach for the highly regioselective functionalization of pyridines and relevant nitrogen-containing heterocycles. This silicon-based protocol is amenable to gram-scale synthesis and also applicable to the late-stage functionalization of pharmaceutically relevant complex molecules.

Unlocking the Nucleophilic Functionalization Potential of a Natural Asphalt: Grafting a Pd(0)-Diethanolamine Complex as a Recyclable Catalyst for Upgrading Biaryl Synthesis

This study introduces a novel method for functionalizing natural asphalt, presenting new opportunities for upgrading asphaltenes from road to a catalyst. The process utilizes a metal-free sonobromination technique in acetic acid to incorporate carbon-halogen substituents onto natural asphalt. These sites are then targeted by nucleophilic substitution with diethanolamine, followed by complexation with Pd(0) to create a unique palladium complex grafted onto natural asphalt. This stabilized complex serves as a heterogeneous and recoverable catalyst in the Suzuki reaction. This complex facilitates the reaction between aryl boronic acids and various ortho-, meta-, and para-substituted aryl halides under mild conditions using polyethylene glycol-400 as the green solvent. The reaction conversion rate is significantly influenced by the leaving group ability of the halides and the electronic and steric effects of the substituents on both reactants. This environmentally friendly process offers a broad substrate scope (24 examples) and achieves excellent yields of biphenyl derivatives. Notably, it employs a naturally derived catalytic support, underscoring its sustainability. This research potentially unlocks the bonding of nucleophiles to the natural asphalt for developing novel functional materials from this renewable resource.

Palladium-Catalyzed Hiyama-Type Coupling of Thianthrenium and Phenoxathiinium Salts

Here, we demonstrate palladium-catalyzed Hiyama-type cross-coupling reactions of aryl thianthrenium or phenoxathiinium salts. By employing stable and inexpensive organosilanes, the arylation, alkenylation, and alkynylation were realized in high efficiency using commercially available Pd(tBu3P)2 as the catalyst, thus providing a reliable method for preparation of biaryls, styrenes, and aryl acetylenes with a broad functional group tolerance under mild conditions. Given the accessibility of aryl thianthrenium or phenoxathiinium salts from simple arenes in a remarkable regioselective fashion, this protocol also provides an attractive approach for the late-stage modification of complex bioactive scaffolds.

Palladium-catalyzed Hiyama cross-couplings of pyrimidin-2-yl tosylates with organosilanes

An efficient palladium-catalyzed Hiyama reaction between various pyrimidin-2-yl tosylates with organosilanes has been developed. The use of CuCl with TBAF as additive is essential for promotion of the construction of the carbon–carbon bond. This procedure shows wide functional group tolerance for electrophilic pyrimidin-2-yl tosylates and has been extended to aromatic amino-substituted pyrimidin-2-yl tosylates, affording the desired C2-aryl and alkenyl pyrimidine derivatives in good to excellent yields.

Recent Advances in the Pd-Catalyzed Coupling of Arylhydrazines and Ammonium Salts via C-N Bond Cleavage

Both arylhydrazines and quaternary ammonium salts are readily accessible or commercially available chemicals that show versatile reactivity in Pd-catalyzed coupling reactions via C-N bond cleavage. A tremendous array of coupling reactions involving reaction partners such as organoborons, aryl silanes, alkenes, alkynes, arylation or alkylation reagents in C-H functionalization and carbonylation reactions are summarized, in which arylhydrazines or quaternary ammonium salts function as aryl or alkyl donors. This account mainly focuses on recent advances in Pd-catalyzed coupling reactions with arylhydrazines or quaternary ammonium salts via C-N bond cleavage, including mechanistic elucidations.

l-Methionine–Pd complex supported on hercynite as a highly efficient and reusable nanocatalyst for C–C cross-coupling reactions

An l-methionine–Pd complex was covalently immobilized on the surface of hercynite (FeAl₂O₄) MNPs, and its catalytic properties were studied in C–C coupling reactions.

Arylhydrazines: novel and versatile electrophilic partners in cross-coupling reactions

Arylhydrazines are extremely valuable compounds in organic chemistry that are widely used for the synthesis of a variety of biologically active molecules such as indoles, indazoles, pyrazoles, aryltriazoles, β-lactams and quinazolines. These compounds have also been widely utilized as arylation agents in oxidative cross-coupling reactions. In this review, we will highlight the most important explorations and developments in the carbon-carbon and carbon-heteroatom (nitrogen, phosphorus, sulfur, and selenium) cross-coupling of arylhydrazines. The literature has been surveyed from 2001 to June 2018.

Denitrogenative palladium-catalyzed coupling of aryl halides with arylhydrazines under mild conditions

A novel, simple, and efficient protocol via Pd(ii)-catalyzed denitrogenative coupling of arylhydrazines with aryl halides under ambient and mild conditions.

Metal-free C–H arylation of imidazoheterocycles with aryl hydrazines

Metal-free C–H arylation of imidazo[1,2-a]pyridines at C-3 position with arylhydrazines in presence of DBU has been developed at room temperature under ambient air.

Arylation of hydrocarbons enabled by organosilicon reagents and weakly coordinating anions

Over the past 80 years, phenyl cation intermediates have been implicated in a variety of C-H arylation reactions. Although these examples have inspired several theoretical and mechanistic studies, aryl cation equivalents have received limited attention in organic methodology. Their high-energy, promiscuous reactivity profiles have hampered applications in selective intermolecular processes. We report a reaction design that overcomes these challenges. Specifically, we found that β-silicon-stabilized aryl cation equivalents, generated via silylium-mediated fluoride activation, undergo insertion into sp3 and sp2 C-H bonds. This reaction manifold provides a framework for the catalytic arylation of hydrocarbons, including simple alkanes such as methane. This process uses low loadings of Earth-abundant initiators (1 to 5 mole percent) and occurs under mild conditions (30° to 100°C).

Poly(o-aminothiophenol)-stabilized Pd nanoparticles as efficient heterogenous catalysts for Suzuki cross-coupling reactions

Poly(o-aminothiophenol)-stabilized Pd nanoparticles have been obtained through a facile one-step route, which exhibit excellent catalytic performance in Suzuki cross-coupling reactions.

Acid-promoted denitrogenative Pd-catalyzed addition of arylhydrazines with nitriles at room temperature

Pd(TFA)₂-catalyzed denitrogenative addition proceeded with selective C–N bond cleavage of arylhydrazines with nitriles under air at room temperature.