1.3.5- Tris benzene reaction with palladium

Vigorous exothermic reaction with benzene + Raney nickel catalyst metals (e.g., lithium calcium barium strontium sodium potassium above 300°C) palladium(II) oxide palladium trifluoride l,l,l-tris(hydroxymethyl)nitromethane + nickel catalyst. 

A mixture of l,4-dibromo-2,5-bis(3-sulfonatopropoxy)benzene 61 (0.78 g, 1.39 mmol), 60 (0.23 g, 1.39 mmol), Na2C03 (0.99 g) in doubly distilled water (47 mL), and DMF (20 mL) was heated at 85°C until the solids were completely dissolved. The resulting solution was cannulated to a 200-mL Schlenk flask with tris[(sulfonatophenyl)phosphine]palladium(0) (0.045 g) and the mixture was stined at 85°C for 10 h. The reaction mixture was concentrated to 25 mL by boiling and filtered. The filtrate was added dropwise to cold acetone (250 mL) to precipitate out the polymer. The polymer was collected by filtration, redissolved in a minimum of hot water, and reprecipitated by cooling. After repeating this procedure twice, the polymer was redissolved in distilled water and dialyzed for 72 h in 3500 gmol 1 cutoff membrane. After drying under vacuum, polymer 63 was obtained in 64% (0.42 g). 

Dinuclear palladium complexes catalyze m-hydroarylation of alkynes with arenes.56 The reaction of 3-hexyne with benzene in the presence of a dinulear palladium complex Pd2R2(M-OH)(//-dpfam) [dpfam = j/V,Ar -bis[2-(diphenyl-phosphino)phenyl]formamidinate, R=/>-Tol] and tri(/z-butyl)borane at 100 °C for 4h affords ( )-3-phenyl-3-hexene quantitatively (Equation (53)). The hydroarylation of 3-hexyne with monosubstituted benzenes ( )-3-aryl-3-hexenes with a 2 1 ratio of the meta- and ra -isomers. This regioselectivity is different from that of the hydroarylation of diphenylacetylene catalyzed by Rh4(GO)12.57... 

A few experiments have been tried with conjugated dienes in the substitution reaction. Preliminary results indicate that they too may react normally. Using palladium acetate in a stoichiometric reaction, benzene and butadiene were found to form 1-phenylbutadiene in about 25% yield (41). Iodobenzene and isoprene react with triethylamine and Pd(PPh3)2(OAc)2 as catalyst at 100° to form ( )-3-methyl-l-phenyl-1, 3-butadiene in 52% yield (42) ... 

During 45 min 3,3-dimethylcyclopropene (8.0g, 118 mmol), precooled to — 78°C, was added dropwise to a suspension of bis(dibenzylideneacetone)palladium (0.77 g, 1.34 mmol) in benzene (20 mL) at 20 °C. The reaction is strongly exothermic, and cooling with a cold water bath was used to prevent the temperature from rising above 45 C. The wine-red color of the mixture persisted throughout the reaction. After complete addition of the cyclopropene, the mixture was stirred at 20°C for an additional 1 h and then distilled. The distillate (23.67 g) was analyzed by GC and consisted of benzene (71.8%), dimer 17 [25.8% yield 6.1 g (76.4%)] and hexamethyl-/ro s-tris-(r-homobenzene 7 [2.1% yield 0.5 g (6.2%)]. 17 can be isolated from this mixture by fractional distillation bp 41 °C/12 Ton. 

Coligands, such as triphenyl-, tributyl- and tri( ec-alkyl)phosphanes, at a palladium/phosphane molar ratio of 1 4 result in the highest selectivity. The use of more polar solvents (e.g. diethyl ether, acetone) decreases the yield of tris-o-homobenzene to about 74%. Instead, up to 24% of the dimer 17 is formed. Increased dimer formation (yield 60.8% 93% conversion s ) also occurs when bulky phosphanes, such as tri(r ri-butyl)phosphane, are employed. Tris-a-homo-benzene is also formed as a minor product (25%) in the reaction of 3,3-dimethylcyclopropene with chlorotris(triphenylphosphane)rhodium and carbon monoxide. The major product in this case arises from carbonylation (see Section 1.1.6.3.3.3.). S S... 

A further refinement of this strategy has recently been shown by the self-assembly of the cage complex (25) formed from the reaction of three palladium(II) ions with l,3,5-tris(4-pyridylmethyl)benzene (24) [34]. A key feature of this process is the critical role played by aromatic guests (such as 4-methoxyphenylacetic acid) in templating the formation of (25). In the absence of guest, only ill-defined, oligomeric metal complexes are formed. 

Arene Amination. Alternative methods for the A-arylation of N-H-containing heterocycles that proceed directly with arenes (i.e., where aryl halides are not required) have emerged in the literature. In a recently reported procedure, a succinimide derivative was iV-arylated using palladium acetate as the catalyst, tri-ferf-butylphosphine as the ligand, and (diacetoxyiodo)benzene as a stoichiometric oxidant. This reaction allows the formation of ster-ically controlled products with monosubstituted arenes, yielding mainly meta- and / ara-arylated products and di- and trisubsti-tuted arenes, mostly providing the products of arylation at the meta-position (eq 15). ... 

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