Carbonylation Palladium acetate-Triphenylphosphine

The carbonylation of Af-benzyl-y-(o-bromophenyl)propylamine to give AT-benzyl-tetrahydro-2-benzazepin-l-one is catalyzed by palladium acetate-triphenylphosphine complex (78JOC1684). On treatment with 2M sodium hydroxide the aminoketone (236) undergoes ring expansion to the 2-benzazepin-l-one (237) in a manner analogous to that outlined in Scheme 28 (80HCA924). 

The insertion of carbon monoxide into readily available 2-bromo-3-aminopropene derivatives can be effected by catalytic quantities of palladium acetate and triphenylphosphine high CO pressures are not required (Scheme 16).38 The /Mactam products presumably arise by palladation,carbonylation, and cyclization as depicted in Scheme 17.38 An extension of this approach to the synthesis of biologically interesting condensed /(-lactams can be expected. 

For the carbonylation of 2-nitrostyrenes to indoles, Soderberg and Shriver found an improvement for this transformation and later on applied it in the synthesis of murrayaquinone A [35-37]. By using palladium acetate (6 mol %) together with triphenylphosphine (24 mol %) as the catalytic system, under 4 bar of carbon monoxide in acetonitrile at 70 °C, indoles were produced in moderate to good yields. Davies s group further improved the methodology [38, 39]. With 0.1 mol % palladium (11) trifluoroacetate [Pd(TFA>2] and 0.7 mol % 3,4,7,8-tetramethyl-l,10-phenanthroline (tm-phen) in DMF at 1 bar of CO and 80 °C, indoles were produced in good to excellent yields. 

The first palladium-catalyzed carbonylations of aryl halides were published in 1974 and 1975 (Equation 17.59). ° Heck first reported the synthesis of benzoates by the reaction of an aryl iodide, carbon monoxide, and an alcohol in the presence of a tertiary amine and catalytic amoimts of the combination of palladium acetate and triphenylphosphine. Concurrently, he reported the synthesis of benzamides from an aryl iodide, carbon monoxide, a primary amine, and a tertiary amine as base catalyzed by the same type of palladium complex. The related reactions of vinyl halides were also reported, and these reactions occurred with retention of the olefin geometry. ... 

Carboxylic acids have been prepared from carbonylation of aUyl bromide over palladium catalysts supported by polyphenol, polyvinylpyrrolidone,polyacrylamide (PAA), modified poly(2,6-dimethyl-l,4-phenylene oxide), and polysulfone- It is unclear under these reducing conditions if gel form metal cluster is involved as the active catalyst. Palladium acetate immobilized on the clay montmoriUonite has proved to be an effective catalyst for the carbonylation of secondary aUylic alcohols, affording a,/3-unsaturated carboxylic acids in moderate yields. However, triphenylphosphine was needed for the acliviva-tion of the catalyst. Palladium catalyst bound to a platinum cluster has been used up to three times for allylic alkylation without a significant loss of its activity. Preliminary study indicated that the Pd—Pt bond remains intact during the catalytic cycle. 

Palladium acetate plus triphenylphosphine catalyse the dimerization and carbonylation of butadiene. The major product is octa-2,7-dien-l-ol, formed by dimerization of the butadiene on the palladium to form (112),... 

An alternative scheme to simultaneous formation of acetaldehyde and acetic anhydride could entail the carbonylation of methyl acetate to acetic anhydride which is subsequently reduced to acetaldehyde and acetic acid. The reaction of acetaldehyde with excess anhydride would form EDA. In fact, Fenton has described production of EDA by the reduction of acetic anhydride using both rhodium and palladium salts as catalysts when modified with triphenylphosphine (26). Two possible mechanisms for the reduction are postulated in equation 16. 

In addition to the successful reductive carbonylation systems utilizing the rhodium or palladium catalysts described above, a nonnoble metal system has been developed (27). When methyl acetate or dimethyl ether was treated with carbon monoxide and hydrogen in the presence of an iodide compound, a trivalent phosphorous or nitrogen promoter, and a nickel-molybdenum or nickel-tungsten catalyst, EDA was formed. The catalytst is generated in the reaction mixture by addition of appropriate metallic complexes, such as 5 1 combination of bis(triphenylphosphine)-nickel dicarbonyl to molybdenum carbonyl. These same catalyst systems have proven effective as a rhodium replacement in methyl acetate carbonylations (28). Though the rates of EDA formation are slower than with the noble metals, the major advantage is the relative inexpense of catalytic materials. Chemistry virtually identical to noble-metal catalysis probably occurs since reaction profiles are very similar by products include acetic anhydride, acetaldehyde, and methane, with ethanol in trace quantities. 

Dichlorobis(triphenylphosphine)-palladium(II), 103 Methyl (trifluoromethylsulfonyl)-methyl sulfone, 193 Nickel carbonyl, 198 Palladium(II) acetate, 232... 

Deprotection of ally I or ally loxy carbonyl derivatives of amino acids. This combination of reagents effects rapid reductive cleavage of allyl or allyloxycarbonyl derivatives of amino acids in CH2CI2 containing a proton donor (/7-NO2C6H5OH, acetic add, H2O). The actual catalyst is probably bis(triphenylphosphine)palladium(0). Benzyl, Boc, and Cbo groups are stable to these conditions. This cleavage does not induce racemization. 

The addition of platinum group metals to the Co-catalyzed carbonylation significantly lowers reaction requirements. A catalyst mixture of 2.7 parts cobalt acetate, 3 parts iodine, 1.2 parts bis(triphenylphosphine)-palladium(II) chloride and 2.4 parts adi-ponitrile converts methanol to acetic acid at 120 C and 25 MPa. 

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