Dipalladium-tris palladium

Tris(dibenzylideneacetone)dipalladium (0) Palladium, tris(l,5-diphenyl-l,4-pentadien-3-one)di- (9) (52409-22-0)... 

B. (E)-4-(2-Phenylethenyl)benzonitrile (2). An oven-dried, 250-mL, three-necked, round-bottomed flask equipped with an argon inlet adapter, rubber septum, glass stopper, and a teflon-coated magnetic stir bar is cooled to room temperature under a flow of argon. The flask is charged successively with bis (tri-tert-butylphosphinc)palladium [(Pd(P(t-Bu)3)2] (0.238 g, 0.466 mmol, 1.5 mol% Pd) (Notes 1, 2), tris(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3) (0.213 g, 0.233 mmol, 1.5 mol% Pd) (Note 3), and... 

Buchwald has shown that, in combination with palladium(II) acetate or Pd2(dba)3 [tris(dibenzylideneacetone)dipalladium], the Merrifield resin-bound electron-rich dialkylphosphinobiphenyl ligand (45) (Scheme 4.29) forms the active polymer-supported catalysts for amination and Suzuki reactions [121]. Inactivated aryl iodides, bromides, or even chlorides can be employed as substrates in these reactions. The catalyst derived from ligand (45) and a palladium source can be recycled for both amination and Suzuki reactions without addition of palladium. 

Cyclocarbonylation of o-iodophenols 503 with isocyanates or carbodiimides and carbon monoxide in the presence of a catalytic amount of a palladium catalyst (tris(dibenzylideneacetone)dipalladium(O) Pd2(DBA)3) and l,4-bis(di-phenylphosphino)butane (dppb) resulted in formation of l,3-benzoxazine-2,4-diones 504 or 2-imino-l,3-benzoxazin-4-ones 505 (Scheme 94). The product yields were dependent on the nature of the substrate, the catalyst, the solvent, the base, and the phosphine ligand. The reactions of o-iodophenols with unsymmetrical carbodiimides bearing an alkyl and an aryl substituent afforded 2-alkylimino-3-aryl-l,3-benzoxazin-4-ones 505 in a completely regioselective manner <1999JOC9194>. On the palladium-catalyzed cyclocarbonylation of o-iodoanilines with acyl chlorides and carbon monoxide, 2-substituted-4f/-3,l-benzoxazin-4-ones were obtained <19990L1619>. 

A dry two-neck flask was charged with amine (1.00 mmol), triflate or bromide (1.20 mmol), base (1.40 mmol), ligand (10 mol%), palladium acetate (Pd(OAc)2) or tris-(dibenzylidene-acetone)dipalladium (0) (Pd2dba3) (5 mol%), and toluene (2.00 mL/mmol of amine). The reaction was flushed with N2 and heated at 80 °C. The mixture was diluted with ether, filtered through a pad of Celite, and the volatile components were removed reduced pressure to give a crude product, which was purified by flash column chromatography on silica gel. 

There are many available complexes of palladium(O) and pal ladiumfl I). T etrak is tri ph e ny I ph osph i ne)pal I ad iu m (0). Pd PPh3)4, and tris dibenzylidene-acetone)dipalladium 0), Pd2 dba)3, or the chloroform complex, Pd2(dba)3-CHCI3 which is air-stable, are the most common sources of... 

Catalyst Preparation Two palladium sources are generally used to form the active precatalysts (1) and (2) in situ, the allylpalladium chloride dimer [12012095-2] and the tris(dibenzylideneacetone)dipalladium(0)-chloroform adduct... 

The crystal structure of this complex is not known, but the structure of the tris(dibenzylideneacetone)dipalladium(o) precursor has been reported [167, 168]. The two palladium atoms have a trigonal planar geometry arising from bonding to the olefinic groups of the three ligands. 

Diaryl ditellurium compounds and tetrakis[triphenylphosphane]palladium reacted in benzene to form the dinuclear complex bis[7t-arenetellurolato]bis[arenetellurolato]bis[tri-phenylphosphane]dipalladium. ... 

Similar studies in an organic solvent yielded almost the same product [66]. Nanostructured particles of amorphous carbon-activated palladium metallic clusters have been prepared (in situ) at room temperature by ultrasound irradiation of an organometallic precursor, tris-//-[dibenzylideneacetone]dipalladium [(p-CH= CH-CO-CH=CH-5 )3Pd2] in mesitylene. Characterization studies show that the product powder consists of nanosize particles, agglomerated in clusters of approximately 800 A. Each particle is found to have a metallic core, covered by a carbonic shell that plays an important role in the stability of the nanoparticles. The catalytic activity in a Heck reaction, in the absence of phosphine ligands, has been demonstrated. 

Palladium can also catalyze cross-coupling between aryl halides and aryl or vinylstannanes and there are examples of application of this reaction in the synthesis of pyrroles and indoles. 1-Tosyl-3-(tri-n-butylstannyl)indole gives good yields of coupling products with vinyl and aryl iodides and triflates. The recommended catalyst is tris-(dibenzylideneacetone)-dipalladium (5 mol%) used with triphenylarsine (10 mol%) (Equation (121)) <94TL2405>. 

Oxidative addition of palladium(O) species into unsaturated halides or triflates provides a popular method for the formation of the a-bound organopalladium(II) species. It is important to use an unsaturated (e.g. aryl or alkenyl) halide or tri-flate, as (3-hydride elimination of alkyl palladium species can take place readily. Oxidative addition of palladium(0) into alkenyl halides (or triflates) occurs stere-ospecifically with retention of configuration. The palladium is typically derived from tetrakis(triphenylphosphine)palladium(0), [Pd(PPh3)4], or tris(dibenzylidene-acetone)dipalladium(O), [Pd2(dba)3], or by in situ reduction of a palladium(II) species such as [Pd(OAc)2] or pd(PPh3)2Cl2]. 

C51H5 lOjPPd, (1-T -1,2,3,4-Tetra(p-tolyl)-4-phenyl-1, 3-butadienyD-(acetylacetonato)(dimethylphenylphosphine)palladium, 44B, 735 C5iHs506P2Pd2f M (Cyclopentadienyl)-M (2-methylallyl)-bis(tri-o-tolylphosphite P)-dipalladium(Pd-Pd), 43B, 1026 Cs2HijoP2Pt, ciS Bis(phenylacetylido)bis(triphenylphosphine)platinum-(II), 43B, 1030... 

For additional discussion about palladium-catalyzed coupling reactions, see also those entries dealing with organopalladium catalysis (e.g. tetrakis(triphenylphosphine)palladium(0), tris-(dibenzylideneacetone)dipalladium-chloroform, and ( )-l-tri-methylsilyl-2-trimethylstannylethylene. 

Related Reagents. Palladium(II) Acetate palladium(II) Chloride l,P-Bis(diphenylphosphino)ferrocene Triphenylphosphine Tris(dibenzylideneacetone)dipalladium-Chloroform. 

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