Palladium® complexes

Complexes of TT-allylpalladium formed by reaction with Pd(0) complexes with allylic derivatives (acetates, ethers, thioethers, and sulfones) can be reduced in a 

4 SULFIDES, THiOETHERS, SULFOXIDES, SULFONES, AND AMINE-OXIDES RSR, RSOR, OR RSO2R  

Sulfoxides and suifones are reduced to sulfides by LAH or AIH3 in an ether medium [H3, HL5], LAH-TiCl4 in THF [AM5], NaBH4-Me3SiCi in THF [GS2], and DIBAH [HL5]. Sulfamides are reduced to amines by Red-Ai in refluxing toluene [GB9, RG3]. SAH, LAH, and AIH3 reduce disulfides to thiols [BYl, CB5, CB7, H3, 

As illustrated in Fig. 7-52, in the related l-[l,T-bis(diphenylphosphino)ferrocene]-palladatetraborane complex, the palladium atom still possesses a pseudo-square-planar environment, two bonds being formed with the phosphorus atoms and the two remaining bonds with the triborane ligand. The cyclopentadienyl rings of the sandwich fragment are parallel and nearly staggered [156]. 

Such bis(diphenylphosphino)ferrocene-palladium complexes commonly undergo a reversible one-electron oxidation, centered on the ferrocene moiety, and an irreversible one-electron reduction, centered on the palladium fragment. The relevant redox potentials are reported in Table 7-29, together with those of related complexes. It must be noted that the ferrocene-based one-electron oxidation leads to ferro-cenium-palladium complexes that are more stable than the free diphenylphosphino-ferrocenium ion. 

Substitution of the two diphenylphosphino substituents for thiolate groups affords a series of complexes, the structure of which is typically represented by that of dichloro[l,r-bis(ibutylsulfido)ferrocene]palladium(ii) shown in Fig. 7-53 [10]. The assembly is similar to that of the preceding bis(diphenylphosphino) complexes, except for the eclipsed and less tilted (1.9°) conformation of the cyclopentadienyl rings of the ferrocene group. 

These complexes also undergo both a one-electron oxidation and a one-electron reduction [10]. Table 7-30 summarizes the relevant redox potentials. 

It is clearly evident that, on complexation to palladium, oxidation of the ferrocene group becomes significantly more difficult. 

PdCl in the presence of NaOAc catalyzes hydrogen transfer from alcohols to 0 [37]. 

Cobalt chloride in diglyme or methyl ethyl ketone - diglyme mixtures catalyzes the oxidation of benzylic groups of alkylaromatics to the corresponding aldehydes or ketones under mild conditions (60 - 

The cobalt nitro complexes [pyCo(saloph)N02] and [pyCo(TPP)N02] catalyze the O -oxidation of primary alcohols to aldehydes and that of secondary alcohols to ketones [40]. Lewis acids (A) like BF. Et O or 

should be present for oxidation to occur. They bind with the 6 

Nitro complexes are also capable of epoxidizing olefins (Section 3. 1.6. ). 

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NMR signals of the amino acid ligand that are induced by the ring current of the diamine ligand" ". From the temperature dependence of the stability constants of a number of ternary palladium complexes involving dipeptides and aromatic amines, the arene - arene interaction enthalpies and entropies have been determined" ". It turned out that the interaction is generally enthalpy-driven and counteracted by entropy. Yamauchi et al. hold a charge transfer interaction responsible for this effect. 

Now we open flask A. We can put a piece of glass and smell it once methanol is evaporated. There is no safrol smell, it s different, it s the dialkoxy derivative of safrol, rxn is completed perfectly. We add now 75 cc of water and stir 45 minutes more. There s a precipitate. We filter the reaction. I don t know what is this, may be also black tar, I thought this may be palladium complexes, this is a... 

Hard carbon nucleophiles of organometallic compounds react with 7r-allyl-palladium complexes. A steroidal side-chain is introduced regio- and stereo-selectively by the reaction of the steroidal 7T-allylpalladium complex 319 with the alkenylzirconium compound 320[283]. 

Addition of several organomercury compounds (methyl, aryl, and benzyl) to conjugated dienes in the presence of Pd(II) salts generates the ir-allylpalladium complex 422, which is subjected to further transformations. A secondary amine reacts to give the tertiary allylic amine 423 in a modest yield along with diene 424 and reduced product 425[382,383]. Even the unconjugated diene 426 is converted into the 7r-allyllic palladium complex 427 by the reaction of PhHgCI via the elimination and reverse readdition of H—Pd—Cl[383]. 

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

Synthesis. The most common staiting materials for palladium complexes are PdCl2 [7647-10-1] and [PdClJ [14349-67-8]. Commercially available materials useful for laboratory-scale synthesis iuclude [Pd2(OOCCH2)J [3375-31-3] [PdCl2(NCCgH )] [14220-64-5] [Pd(acac)2] [14024-61-4] [PdCl2(cod)] [12107-56-1], and [Pd(P(CgH5)3)J [14221-01-3]. 

Succinic anhydride is manufactured by catalytic hydrogenation of maleic anhydride [108-31-6]. In the most widely used commercial process this reaction is performed in the Hquid phase, at temperatures of 120—180°C and at moderate pressures, in the range of 500—4000 kPa (72—580 psi). Catalysts mentioned in the patent Hterature include nickel (124), Raney nickel (125,126), palladium on different carriers (127,128), and palladium complexes (129). The hydrogenation of the double bond is exothermic Ai/ = —133.89 kJ/mol (—32 kcal/mol) (130). 

Alkenyl zirconium complexes derived from alkynes form C—C bonds when added to aHyUc palladium complexes. The stereochemistry differs from that found in reactions of corresponding carbanions with aHyl—Pd in a way that suggests the Cp2ZrRCl alkylates first at Pd, rather than by direct attack on the aUyl group (259). 

In hydrocarboxylation, the Reppe reaction, the catalyst can be nickel or cobalt carbonyl or a palladium complex where R = H or alkyl. 

The nickel or cobalt catalyst causes isomerization of the double bond resulting in a mixture of C-19 isomers. The palladium complex catalyst produces only the 9-(10)-carboxystearic acid. The advantage of the hydrocarboxylation over the hydroformylation reaction is it produces the carboxyUc acids in a single step and obviates the oxidation of the aldehydes produced by hydroformylation. 

Porphyrin, octaethyl-, palladium complex cyclic voltammetry, 4, 399 <73JA5140)... 

Seven procedures descnbe preparation of important synthesis intermediates A two-step procedure gives 2-(HYDROXYMETHYL)ALLYLTRIMETH-YLSILANE, a versatile bifunctional reagent As the acetate, it can be converted to a tnmethylenemethane-palladium complex (in situ) which undergoes [3 -(- 2] annulation reactions with electron-deficient alkenes A preparation of halide-free METHYLLITHIUM is included because the presence of lithium halide in the reagent sometimes complicates the analysis and use of methyllithium Commercial samples invariably contain a full molar equivalent of bromide or iodide AZLLENE IS a fundamental compound in organic chemistry, the preparation... 

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

The reversible reaction of tri-n-butylstannylfuran with the cyclometallated palladium complex 24 yields the ti C) coordinated 2-furyl complex 25 (98JA11016). 

It was found [99JCS(PI )3713] that, in all cases, the formation of the deiodinated products 38 and 39 was accompanied by formation of the diynes 40 which were isolated in 60-90% yield. The authors believed that the mechanism of deiodination may be represented as an interaction ofbis(triphenylphosphine)phenylethynyl-palladium(II) hydride with the 4-iodopyrazole, giving rise to the bisftriphenylphos-phine)phenylethynyl palladium(II) iodide complex which, due to the reductive elimination of 1 -iodoalkyne and subsequent addition of alk-1 -yne, converts into the initial palladium complex. Furthermore, the interaction of 1-iodoalkynes with the initial alkyne in the presence of Cul and EtsN (the Cadiot-Chodkiewicz reaction) results in the formation of the observed disubstituted butadiynes 40 (Scheme 51). 

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