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Both palladium and copper complexes of the compound exhibit high activity for the coupling of aryl halides and aryl tosylates with various amides. [1] It is also an efficient ligand for several commonly used C–C bond-forming cross-coupling reactions, including the Negishi, Suzuki, and the copper-free Sonogashira coupling reactions.
Many mechanisms exist reflecting the myriad types of cross-couplings, including those that do not require metal catalysts. [7] Often, however, cross-coupling refers to a metal-catalyzed reaction of a nucleophilic partner with an electrophilic partner. Mechanism proposed for Kumada coupling (L = Ligand, Ar = Aryl).
Pd-BrettPhos complexes catalyze the coupling of weak nucleophiles with aryl halides. Such catalysts are selective for the monoarylation of primary amines. Other applications of BrettPhos in catalysis include trifluoromethylation of aryl chlorides, [45] the formation of aryl trifluoromethyl sulfides, [46] and Suzuki-Miyaura cross-couplings. [47]
The most common type of coupling reaction is the cross coupling reaction. [1] [2] [3] Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed cross coupling reactions. [4] [5] Broadly speaking, two types of coupling reactions are recognized:
The coupling of 2-chlorobenzoic acid and aniline is illustrative: [4] C 6 H 5 NH 2 + ClC 6 H 4 CO 2 H + KOH → C 6 H 5 N(H)−C 6 H 4 CO 2 H + KCl + H 2 O. A typical catalyst is formed from copper(I) iodide and phenanthroline. The reaction is an alternative to the Buchwald–Hartwig amination reaction.
Many decarboxylative cross coupling reactions involve the breaking of sp 2 C–COOH and sp C–COOH bonds, therefore subsequent studies have attempted to enable cross coupling with sp 3 C carboxylic acids. One such reaction by Shang et al. described a palladium catalyzed cross coupling that enables the formation of functionalized pyridines ...
Cl(CH 2) n Cl + 2 NaPPh 2 → Ph 2 P(CH 2) n PPh 2 + 2 NaCl. Diphosphine ligands can also be prepared from dilithiated reagents and chlorophosphines: [4] XLi 2 + 2 ClPAr 2 → X(PAr 2) 2 + 2 LiCl (X = hydrocarbon backbone) This approach is suitable for installing two dialkylphosphino groups, using reagents such as chlorodiisopropylphosphine.
The Hiyama coupling is a palladium-catalyzed cross-coupling reaction of organosilanes with organic halides used in organic chemistry to form carbon–carbon bonds (C-C bonds). This reaction was discovered in 1988 by Tamejiro Hiyama and Yasuo Hatanaka as a method to form carbon-carbon bonds synthetically with chemo - and regioselectivity . [ 1 ]