Palladium chloride carbonyl compounds

The allylation of aldehydes can be carried out using stannous chloride and catalytic cupric chloride or copper in aqueous media." In-situ probing provides indirect (NMR, CV) and direct (MS) evidence for the copper(I)-catalyzed formation of an allyltrihalostannane intermediate in very high concentration in water (Scheme 8.6). Hydrophilic palladium complex also efficiently catalyzes the allylation of carbonyl compounds with allyl chlorides or allyl alcohols with SnCl2 under aqueous-organic... 

Palladium catalysts, 10 42 14 49 16 250 Palladium-catalyzed carbonylation, 13 656 Palladium chloride/copper chloride, supported catalyst, 5 329 Palladium compounds, 19 650-654 synthesis of, 19 652 uses for, 19 653-654 Palladium films, 19 654 Palladium membranes, 15 813 Palladium monoxide, 19 651 Palladium oxide, 19 601... 

The mechanism of the Zn chloride-assisted, palladium-catalyzed reaction of allyl acetate (456) with carbonyl compounds (457) has been proposed [434]. The reaction involves electroreduction of a Pd(II) complex to a Pd(0) complex, oxidative addition of the allyl acetate to the Pd(0) complex, and Zn(II)/Pd(II) transmetallation leading to an allylzinc reagent, which would react with (457) to give homoallyl alcohols (458) and (459) (Scheme 157). Substituted -lactones are electrosynthesized by the Reformatsky reaction of ketones and ethyl a-bromobutyrate, using a sacrificial Zn anode in 35 92% yield [542]. The effect of cathode materials involving Zn, C, Pt, Ni, and so on, has been investigated for the electrochemical allylation of acetone [543]. 

The oxidation of olefins to carbonyl compounds by palladium (II) ion can be regarded as an addition of a palladium hydroxide group to the olefin followed by a hydrogen shift. Kinetic evidence suggests the following mechanism for the oxidation of ethylene by palladium chloride in aqueous solution containing excess chloride ion 21, 49, 99). 

Next to the cyclopropane formation, elimination represents the simplest type of a carbon-carbon bond formation in the homoenolates. Transition metal homoenolates readily eliminate a metal hydride unit to give a,p-unsaturated carbonyl compounds. Treatment of a mercurio ketone with palladium (II) chloride results in the formation of the enone presumably via a 3-palladio ketone (Eq. (24), Table 3) [8], The reaction can be carried out with catalytic amounts of palladium (II) by using CuCl2 as an oxidant. Isomerization of the initial exomethylene derivative to the more stable endo-olefin can efficiently be retarded by addition of triethylamine to the reaction mixture. 

In the case of experiments performed under the conditions of run 6, but in the presence of 1 ml of methanol, 1.6 equivalent of dimethyl carbonate was obtained according to GC analysis. No dimethyl carbonate was observed in the absence of hydrogen chloride. Therefore, in the early stage of the carbonylation of 3, Pd/C is partly oxidized to palladium chloride (eqn. 2). This compound reacts in turn with CO and MeOH to give, according to one of the routes described in Scheme 2, dimethyl carbonate and a zerovalent palladium complex (noted [Pd]). 

Palladium-Catalyzed Conjugate Reduction of a,s-Unsaturated Carbonyl Compounds with Diphenylsilane and Zinc Chloride Cocatalyst a,B-Dihydro-B-Ionone... 

The oxidation of olefins to carbonyl compounds by means of palladium chloride catalysts (and involving intermediate organopalladium compounds) 22, 225, 226),... 

Palladium chloride and metallic palladium are useful for carbonylating olefinic and acetylenic compounds. Further, palladium is active for decarbonylation of aldehydes and acyl halides. Homogeneous decarbonylation of aldehydes and acyl halides and carbonylation of alkyl halides were carried out smoothly using rhodium complexes. An acyl-rhodium complex, thought to be an intermediate in decarbonylation, was isolated by the oxidative addition of acyl halide to chlorotris(triphenylphosphine)rhodium. The mechanisms of these carbonylation and decarbonylation reactions are discussed. 

Alkyne cyclotrimerization occurs at various homogeneous and heterogeneous transition metal and Ziegler-type catalysts [7], Substituted benzenes have been prepared in the presence of iron, cobalt, and nickel carbonyls [8] as well as trialkyl- and triarylchromium compounds [9]. Bis(acrylonitrile)nickel [10] and bis(benzonitrile)palladium chloride [11] catalyze the cyclotrimerization of tolane to hexaphenylbenzene. NiCl2 reduced by NaBH4 has been utilized for the trimer-ization of 3-hexyne to hexaethylbenzene [12]. Ta2Cl6(tetrahydrothiophene)3 and Nb2Cl6(tetrahydrothiophene)3 as well as 7 -Ind-, and 77 -Ru-rhodium... 

Nickel, palladium and copper catalysts can effect a variety of C — C bond-forming reactions P to the ester carbonyl via j8-zinc esters. These include 1,4-addition to a,jS-unsaturated carbonyl compounds (copper), arylation with aryl halides (palladium, nickel), allylation with allyl chloride (copper), and acylation with acyl chlorides (palladium, copper). " ... 

Carbonylation of various unsaturated compounds in the presence of palladium chloride is described by Tsuji el al.4 s Since olefins form complexes with palladium chloride, these apparently are involved, but generally have not been prepared directly. In the case of simple olefins the general reaction is considered to be ... 

The palladium chloride-coppeifll) chloride couple (28, 29) used industrially in the Wacker process oxidizes olefins to carbonyl compounds. Experimental kinetic and isotope effect data (30) seem to indicate that a TT-olefin complex is initially formed in a series of preequilibrium steps. The rate-determining step is postulated to be a rearrangement of the TT-olefin complex to a cr-complex followed by the final breakdown of the cr-complex to products. Figure 13 depicts the widely accepted Henry mechanism (31). 

Wacker process /wak-er/ An industrial process for making ethanal (and other carbonyl compounds). To produce ethanal, ethene and air are bubbled through an acid solution of palladium(II) chloride and cop-per(ll) chloride (20-60°C and moderate pressure) ... 

---