Palladium dichloride complexes

A similar approach was taken for the synthesis of 45 by Miyaura. " Shaughnessy and Booth synthesized the water-soluble alkylphosphine 46, and found it to provide very active palladium catalysts for the reaction of aryl bromides or chlorides with boronic acids. The more sterically demanding ligand 47 was shown to promote the reactions of aryl chlorides with better results than 46. Najera and co-workers recently reported on the synthesis of di(2-pyridyl)-methylamine-palladium dichloride complexes 48a and 48b, and their use in the coupling of a variety of electrophiles (aryl bromides or chlorides, allyl chlorides, acetates or carbonates) with alkyl- or arylboronic acids very low catalyst loadings at Palladium-oxime catalysts 8a and 8b) have also been developed. In conjunction with... 

A recent addition to this field is the polymer-supported di(2-pyridyl)-methylamine-palladium dichloride complex covalently attached to a styrene-alt-maleic acid anhydride copolymer. Turnover numbers as high as 105 were reported and a couple of microwave-heated Suzuki-Miyaura reactions could be performed in neat water [134], 2-Pyridinealdoxime-based Pd(II)-... 

In 2005 and 2006, Mori et al. reported the arylation of heterocycles with aryl iodides using palladium dichloride complexes as catalysts and silver nitrate or fluoride as activators (Scheme 10.50). The best coupling conditions were obtained with a combination of silver nitrate and potassium fluoride.82... 

The bis(acetonitrile)palladium dichloride catalyzed rearrangement of R,E)-4 results in a 7 3 product distribution of 5 and 6. but a virtually complete 1.4-chirality transfer is observed (S 98 % ec)994. A possible mechanism for this type of reaction is that the palladium dichloride diene complex undergoes oxidative addition of the allylic C—C bonds to form a bis( /3-al-lyl)palladium(IV) intermediate 7 or 8, which can then reductively eliminate to give a palladium ) dichloride complex of the Cope product994 (for another mechanism see p 3572). 

Palladium(V) complexes, 5, 1100 Palladium compounds photothermography, 6, 118 Palladium dichloride solid state oligomerization, 1, 187 Palladium(II) salts sensitizers... 

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. 

The palladium(II)-catalyzed oxidation of allenes with chloride was studied by Hege-dus et al. [3], In this reaction the dimeric products 4 and 6 as shown in Scheme 17.4 were obtained. The (allene)palladium(II) complex formed can react with chloride ions in two different ways (Scheme 17.4) [4]. Attack at the terminal carbon gives a vinylpalladium intermediate 2 whereas attack at the middle carbon produces a 2-chloro(jt-allyl)palladium complex 3. The former complex is the kinetic intermediate (k2 > kj) and is in equilibrium with the (allene)palladium complex. The 2-chloro(jt-allyl)palladium complex is formed more slowly but is more stable and has been isolated [2]. The vinyl complex can undergo further reaction with excess allene to give a new (jt-allyl)palladium complex, which undergoes attack with chloride to give the observed dimer 6 [3]. The dichloride from attack on the 2-chloro-(jT-allyl)palladium complex 3 was not observed. 

Mizugaki et al. 74) have recently utilized thermomorphic properties of Pd(0)-complexed phosphinated dendrimers for dendritic catalyst recycling. Using the method developed by Reetz 16), they prepared dendritic ligands containing, respectively, 2, 8, 16, and 32 chelating diphosphines. Palladium dichloride was com-plexed to the dendrimers, and a reduction in the presence of triphenylphosphine gave the Pd(0)-complexed dendrimers (80—83). The dendritic complexes were active... 

Palladium dichloride forms polymeric carhonyl complexes when the dry chloride is heated in a stream of carhon monoxide charged with methane vapor. Such complexes include [PdCl2(CO)n] and [PdCl(CO)2]n. The reaction also occurs in aqueous phase resulting in decolorization of the solution. 

The formation of some silylated i73-allylic complexes has been, however, achieved by reacting substituted silyl olefins with bis(benzonitrile)palladium dichloride. The mechanism is rather complex and two olefin molecules are incorporated in the final i -allylic ligand 169) ... 

Palladium dichloride forms more easily both cis and trans complexes with monophosphines and it provides a better example. Yam et al. described cis to trans isomerization of palladium dichloride and a similar ligand to 20 containing an... 

The heterobinuclear complex [PdPtCl2( -dppm)2] can also be prepared by treating the product from the reaction of dppm and [Pd(PPh3)4] with [PtCl2(NCBu,)2].76 The corresponding bromide, iodide and thiocyanate dipalladium and palladium-platinum complexes have been prepared by metathesis of the dichloride (9) with NaX.76... 

One of the first significant advances in the chemistry of TT-allylpalladium complexes was the discovery that alkenes could be directly converted into the corresponding allyl complex by substitution into the allylic C—H bond. A variety of recipes have now been reported that can accomplish this transformation. Initially, palladium chloride17-23 or its more soluble forms, sodium or lithium tetrachloropalladate24-27 and bisacetonitrile palladium dichloride,28-30 in alcohol or aqueous acetic acid solvent were employed. The use of palladium trifluoroacetate, followed by counterion exchange with chloride, represents the mildest and most effective means available to accomplish this reaction.31... 

Several tr-allyl palladium chloride complexes have been prepared from steroidal olefins. Reaction of cholest-4-ene (65), for example, with bis(benzonitrile)palladium dichloride produced dimeric complexes of structures (66) and (67) (76). 

Complex compounds with halide bridges are prepared by immediate interaction of unsaturated hydrocarbons with metal salts (Sec. 2.2.4.1). Their examples are classic 7i-complexes of the type 123 which are characteristic for fi 8-metals [75]. Such complexes are also formed by the method of ligand exchange. The bridges of this type are widespread in products of cyclometallation reactions with the use of metal halides (Sec. 2.2.5.1) 371-374, 381, 382 [41,46,48]. An example of such a synthesis is the reaction of arylhydrazones of 2-oxopropionic aldehyde and benzoylformalde-hyde, as well as butadiene-2,3-dione 635, with palladium dichloride, leading (3.71) to dipalladium complexes 636 [88] ... 

The design of well-defined complexes has led to better yields in coupling products from aryl chlorides under, sometimes, smoother reaction conditions. (NHC)-palladium(O) complexes [149-151] or NHC-palladium dichloride dimers [ 152] have been reported to catalyze the coupling of aryl chlorides and amines in high yields (Fig. 5). The latter system even allowed the reaction to be carried out under aerobic reaction with technical grade solvent without significant loss of activity. 

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