Palladium tetrakis

By Replacement of Zerovalent Isocyanide Derivatives. This method was described for preparing the tris and tetrakis palladium (0) derivatives with tertiary aromatic phosphines and phosphites 129). It might be extended to nickel. 

Tetrakis(triphenylphosphine) palladium [14221-01-3] M 1155.58, m 100-105"(dec). Yellow crystals from EtOH. It is stable in air only for a short time, and prolonged exposure turns its colour to orange. Store in an inert atmosphere below room temp in the dark. [7 Chem Soc 1186 1957.]... 

A variety of catalysts, solvents and amines as base can be employed for the Sonogashira reaction. Typical conditions are, e.g. tetrakis(triphenylphosphine)palladium(0)... 

A synthetically useful virtue of enol triflates is that they are amenable to palladium-catalyzed carbon-carbon bond-forming reactions under mild conditions. When a solution of enol triflate 21 and tetrakis(triphenylphosphine)palladium(o) in benzene is treated with a mixture of terminal alkyne 17, n-propylamine, and cuprous iodide,17 intermediate 22 is formed in 76-84% yield. Although a partial hydrogenation of the alkyne in 22 could conceivably secure the formation of the cis C1-C2 olefin, a chemoselective hydrobora-tion/protonation sequence was found to be a much more reliable and suitable alternative. Thus, sequential hydroboration of the alkyne 22 with dicyclohexylborane, protonolysis, oxidative workup, and hydrolysis of the oxabicyclo[2.2.2]octyl ester protecting group gives dienic carboxylic acid 15 in a yield of 86% from 22. 

Because the Sonogashira coupling process outlined in Scheme 18 is initiated by the in situ reduction of palladium(n) to palladium(o), it would be expected that palladium(o) catalysts could be utilized directly. Indeed, a catalytic amount of tetrakis(triphenylphosphine)-... 

The reaction of 5-chloro-l,4-benzoxazepine (4), whose preparation is described below, with tributyltin hydride catalyzed by tetrakis(triphenylphosphane)palladium(0) gives 1,4-benzox-azepine (5).32... 

A solution of 1.5 mol equiv of butyllithium in hexane is added to 1.5 mol equiv of a 1 M solution of hexabutylditin in THF at 0 C under nitrogen, and the mixture is stirred for 20 min. The solution is cooled to — 78 °C and a solution of 1.5 mol equiv of diethylaluminum chloride in toluene is added. After stirring for 1 h at — 78 °C, a solution of 0.05 mol equiv of [tetrakis(triphenyl)phosphine]palladium(0) in THF is added followed by a solution of the allyl acetate in THF. The mixture is warmed to r.t., and stirred until the allyl acetate has reacted (TLC). The solution is cooled to 0°C, and an excess of aq ammonia slowly added. After an aqueous workup, the products arc isolated and purified by flash chromatography on silica gel using 1 % triethylamine in the solvent to avoid acid-induced loss of stannane. 

Allylic acetates of either geranyl acetate or neryl acetate reacted with the sodium salt of methyl phenylsulfonyl acetate in the presence of tetrakis(triphenylphosphine palladium) affording the corresponding olefin, with a retained geometry at the primary carbon... 

Tetrakis(tripheiiylphosphine)palladium(0) is often used for this reaction. However, Pd(II) complexes such as bis(triphenylphosphine)palladium dichloride or palladium acetate are also commonly employed for convenience, as they are stable in ah. The base is typically a secondary or tertiary amine such as triethy-lamine. Weak bases such as sodium (potassium) acetate, bicarbonate, or carbonate are also used. 

Tetraalkylammonium hydroxides, 405 Tetrabutoxytitanium, 70 Tetrabutyltin, 68 Tetraethoxysilane (TEOS), 348 Tetrahydrofuran (THF), 348 Tetrakis(triphenylphosphine)palladium(0), 486... 

Benzy 1-6-chloropurine reacts with tetrakis(triphenylphosphine)palladium in DCE to give, not only the 6-purinylpalladium(Il) complex 102, but a dinuclear complex 103. Using Stille coupling (RSnBus) only the 6-substituted purine is obtained <96ACS462>. 

In 1988, Linstrumelle and Huynh used an all-palladium route to construct PAM 4 [21]. Reaction of 1,2-dibromobenzene with 2-methyl-3-butyn-2-ol in triethylamine at 60 °C afforded the monosubstituted product in 63 % yield along with 3% of the disubstituted material (Scheme 6). Alcohol 15 was then treated with aqueous sodium hydroxide and tetrakis(triphenylphosphine)palladium-copper(I) iodide catalysts under phase-transfer conditions, generating the terminal phenylacetylene in situ, which cyclotrimerized in 36% yield. Although there was no mention of the formation of higher cyclooligomers, it is likely that this reaction did produce these larger species, as is typically seen in Stephens-Castro coupling reactions [22]. 

The Suzuki-Miyaura synthesis is one of the most commonly used methods for the formation of carbon-to-carbon bonds [7]. As a palladium catalyst typically tetrakis(triphenylphosphine)palladium(0) has been used, giving yields of44—78%. Recently, Suzuki coupling between aryl halides and phenylboronic acid with efficient catalysis by palladacycles was reported to give yields of 83%. 

Bromobenzaldehyde and 4-fluorophenylboronic acid were coupled in DMF using tetrakis(triphenylphosphine)palladium(0) as catalyst [85] (see a more extended description in [42]). 

Like the palladium(II) complexes, the platinum(II) porphyrins show appreciable phosphorescence even in aqueous media at room temperature in one study,169 singlet oxygen quantum yields ranged from 0.1 to 0.9 and were strongly influenced by dimerization/aggregation. Platinum(II) 5,10,15,20-tetrakis(/>-carboxyphenyl)porphyrin and platinum(II)coproporphyrin-I ((36) for Pd read Pt) have been studied as phosphorescent labels of antibodies for use in time-resolved microscopy.189... 

The synthesis of the second Stille coupling partner 34 was efficiently achieved in three steps. First, 2-bromojuglone (36) [28] was protected as its methoxymethyl ether (46, Scheme 3.7). The quinone was reduced using sodium thiosulfate, and the resulting hydroquinone was protected with methoxymethyl chloride to afford the arene 47. Finally, stannylation using tetrakis-(triphenylphosphine)palladium and hexabutylditin [29] afforded the cross-coupling partner 34 in high yield. 

C. 4-(3-Cyclohexenyl)-2-phenylthio-1-butene. To the above solution of the borane derivative, 0.809 g (0.700 mmol) of tetrakis(triphenylphosphine)palladium(0) (Note 9), 1.47 g (5.60 mmol) of triphenylphosphine (Note 10), 35 mL of 3 M potassium phosphate in water (Note 11), and finally 15.1 g (70.0 mmol) of 1-bromo-1-phenylthioethene are added and the resulting mixture is heated at reflux for 3 hr with stirring. The light brown solution is cooled to room temperature and treated with 6.4 g... 

The preparation of tetrakis(triphenyiphosphine)palladium(0) is described.4 It is also available from Aldrich Chemical Company, Inc. 

Tetrakis(triphenylphosphine)palladium(0) Palladium, tetrakis(triphenylphosphine)-(8) Palladium, tetrakis(triphenylphosphine)-, (T-4)- (9) (14221-01-3) Triphenylphosphine Phosphine, thphenyl- (8,9) (603-35-0)... 

Dialkylindolines and 1,3-dialkylindoles are formed in poor yield (<10%) from the reaction of ethyl- or phenymagnesium bromide with 2-chloro-N-methyl-N-allylaniline in the presence of catalytic quantities of (bistriphenylphosphine)nickel dichloride.72 In a modification of this procedure, the allyl derivatives can be converted by stoichiometric amounts of tetrakis(triphenylphosphine)nickel into 1,3-dialkylindoles in moderate yield72 (Scheme 43) an initial process of oxidative addition and ensuing cyclization of arylnickel intermediates is thought to occur. In contrast to the nickel system,72 it has proved possible to achieve the indole synthesis by means of catalytic quantities of palladium acetate.73 It is preferable to use... 

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