Palladium compounds carbonylation

The usual experimental procedure for CO insertion is to heat a solution of the alkyl or aryl complex with a high pressure of carbon monoxide. However, many of these reactions take place under mild conditions. A high pressure of carbon monoxide may only be necessary to ensure a high yield of acyl derivative in a reversible reaction. The following examples illustrate some of the conditions used. Note that the palladium compound carbonylates more readily than its platinum analog C2H5Mn(CO)s also reacts more easily than C2H5Re(CO)s. 

Organomercurial carbonylation. Use of Co2(CO)g as a stoichiometric and as a catalytic reagent Organic synthesis reactions using palladium compounds Decarbonylation reactions using transition metal compounds... 

The palladium-catalyzed carbonylation of aryl halides in the presence of various nucleophiles is a convenient method for synthesizing various aromatic carbonyl compounds (e.g., acids, esters, amides, thioesters, aldehydes, and ketones). Aromatic acids bearing different aromatic fragments and having various substituents on the benzene ring have been prepared from aryl iodides at room temperature under 1 atm... 

Hydroboration and oxidation of 160 yields an alcohol that is subsequently oxidized with PDC to give ketone compound 161. Enolization and triflation converts this compound to enol triflate 162, which can be further converted to x,/i-unsaturated ester 163 upon palladium-mediated carbonylation methox-ylation. The desired alcohol 164 can then be readily prepared from 163 via DIBAL reduction. Scheme 7 50 shows these conversions. 

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... 

Allenic esters can be generated by palladium-catalyzed carbonylation of propargyl compounds (see Section 7.2.6). Under the reaction conditions applied, however, succeeding reactions occur directly in many cases, for instance by introduction of a second ester function. Many examples of such carbonylation reactions of allenic esters were summarized in a review by Tsuji and Mandai [136],... 

In a slightly less convenient procedure, but one which has general versatility, carbonylation of aryl (or vinyl) palladium compounds produces aryl, heteroaryl, and vinyl carboxylic acids. As with the other procedures, immediate upon its formation, the carboxylate anion migrates to the aqueous phase. Consequently, haloaromatic acids can be obtained from dihaloarenes, without further reaction of the second halogen atom, e.g. 1,4-dibromobenzene has been carbonylated (90% conversion) to yield 4-bromobenzoic acid with a selectivity for the monocarbonylation product of 95%. Additionally, the process is economically attractive, as the organic phase containing the catalyst can be cycled with virtually no loss of activity and ca. 4000 moles of acid can be produced for each mole of the palladium complex used [4],... 

The reaction of alcohols with CO can also be catalysed by palladium iodides, and various ligands or solvents. Acetic acid is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a palladium compound, an ionic iodide compound, a sulfone solvent at conditions similar to those of the rhodium system (180 °C, 60 bar), and, in some cases, traces of a nickel-bipyridine compound were added. Sulfones or phosphine oxides play a stabilising role in preventing metal precipitation [26], Palladium(II) salts catalyse the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective [27],... 

Trifluoroalanine has also been prepared by reducing trifluoropyruvate imines (ethyl trifluoropyruvate is available commercially it is prepared either from per-fluoropropene oxide or by trifluoromethylation of ethyl or f-butyl oxalate). These imines are obtained by dehydration of the corresponding aminals or by Staudinger reaction. They can also be obtained by palladium-catalyzed carbonylation of trifluoroacetamidoyl iodide, an easily accessible compound (cf. Chapter 3) (Figure 5.4). Reduction of the imines affords protected trifluoroalanines. When the imine is derived from a-phenyl ethyl amine, an intramolecular hydride transfer affords the regioisomer imine, which can further be hydrolyzed into trifluoroalanine. ... 

Palladium-catalyzed allylic oxidations, in contrast, are synthetically useful reactions. Palladium compounds are known to give rise to carbonyl compounds or products of vinylic oxidation via nucleophilic attack on a palladium alkene complex followed by p-hydride elimination (Scheme 9.16, path a see also Section 9.2.4). Allylic oxidation, however, can be expected if C—H bond cleavage precedes nucleophilic attack 694 A poorly coordinating weak base, for instance, may remove a proton, allowing the formation of a palladium rr-allyl complex intermediate (89, path by694-696 Under such conditions, oxidative allylic substitution can compete... 

Carbonylation of organometallic reagents.1 The review covers the carbon-ylation of organolithium, -magnesium, -boron, -mercury, and -palladium compounds (86 references). 

Unsymmetricatl ketones can be obtained by the palladium-catalyzed carbonylation of aryl, alkyl and vinyl bromides and iodides in the presence of tetraalkyl- or tetraaryl-tin compounds (equation 113).489,490 The catalyst precursors used were complexes (102), (107) and [PdCI2(AsPh3)2]. 

Palladium compounds are effective catalysts for the selective oxidative transformation of primary and secondary alcohols into carbonyl compounds. Although conventional PdCl2/CuCl2 catalysts can operate at 70-120 °C and under 02 pressure (3 atm),465 milder procedures using a PdCl2/NaOAc mixture are effective at room temperature and atmospheric 02 pressure (equation... 

After separation of the desired major diastereoisomer 154, the removal of the chiral auxiliary furnished vinyl compound 151 in enantiomerically pure form. The latter was directly converted to the 9-membered lactam 144 in 58% yield via a palladium-catalyzed carbonylation (10 atm CO, HCOOH, DME, 150°C). Removal of the methyl ester as previously described furnished (-)-rhazinilam. This elegant work constitutes the first asymmetric total synthesis of the natural product. 

When the homocoupling reaction is performed in the presence of carbon monoxide, the palladium-catalyzed carbonylative coupling of organolead compounds takes place (Equation (104)). Thus, organolead triacetates can be carbonylated in the presence of Pd2(dba)3, CHC13 (5 mol%) and NaOMe (5 equiv.) in acetonitrile under atmospheric pressure of carbon monoxide at room temperature to afford good yields of the symmetrical ketones.118... 

In 1979 the reaction of benzyl and aryl halides was reported with mechanistic discussions [8, 9]. The first palladium-catalyzed carbonylative coupling of organic halides with organotin compounds was reported by Tanaka in the same year (Scheme 4) [10,11]. 

Keywords. Aryl halides, Arylation, Palladium catalysts. Carbonyl compounds. Aromatic compounds... 

The insertion of CO into palladium carbon bonds is a common step in many palladium-catalyzed carbonylation reactions and polymerizations. This reaction takes place under moderate CO pressure (1-3 atm). From the range of compounds that can be carbonylated, it can be inferred that CO will insert into alkyl, aryl, and alkynic bonds (equation 13). One of the few types of Pd-C bonds inert to CO insertion is the Pd-acyl bond, thus only single carbonylations are normally observed. However, a few examples of double carbonylation have been reported. In the case of palladium-catalyzed formation of PhCOCONEt2 from Phi, CO, and NHEt2, reductive elimination from a bisacyl complex has been established as the mechanism, rather than CO insertion into a Pd-acyl bond. 

The first important application of palladium compounds for industrial and laboratory syntheses was the oxidation of alkenes to carbonyl compounds, vinyl acetates, and related... 

The palladium-catalyzed carbonylative coupling reaction of alkenyl halides with organoboron compounds in the presence of carbon monoxide is a valuable procedure for the synthesis of unsymmetrical ketones. " ... 

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