Palladium-catalysed reactions carbonylation

However, for other palladium catalysed reactions of organozinc iodides with electrophiles, THF is a good choice of solvent. The incompatibility of THF and acid chlorides at ambient temperature can also be overcome, in some cases, by the use of a carbonylative cross-coupling in which an iodobenzene derivative is used as the precursor.17... 

Recently developed palladium-catalysed double carbonylation reactions provide a convenient method for introducing two reactive carbonyl groups into organic substrates. This reactivity has been exploited in syntheses of isatin and quinoline derivatives (Scheme 56).79... 

Trost and his co-workers have extended their work on the addition of the 1trimethylenemethane1 palladium complex to carbonyl compounds and shown that addition of 5 mole% of tri-n-butyltin acetate to the palladium-catalysed reaction of... 

Halopyridines or pyridinyl triflates take part in palladium-catalysed reactions -Heck, carbonylation, and coupling reactions, for example with alkynes, or in Suzuki reactions with arylboronic acids,and cyclopropylboronic acids. 

The palladium catalysed reaction -follows a rate law which is independent on the substrate concentration, but dependent on the CO pressure. In a later work, a AS =-233 J mol " "K, instead o-f -414, has been reported -for this react i on [1843, tor which it has been confirmed a zero order in substrate and first order in each metallic component and in CO pressure. The carbonyl ation of an intermediate complex forming the isocyanate is considered the rate determinin step in the palladium-catalysed reaction. In this work[183j, the oxidative addition of the nitro compound to the catalyst was considered a more likely rate determining step in the case of the rhodium-catalysed reaction. 

Further work on the palladium-catalysed reaction of butadiene with carbonyl compounds, which gives tetrahydropyrans, has been reported. The d-hydroxyaldehydes (237), obtained by the action of alkyl Grignard reagents on glutaraldehyde, form cyclic hemiacetals (238) which may be... 

In the palladium-catalysed carbonylation of aryl bromides to yield benzaldehyde derivatives, IV-formylsaccharin is used as the source of the acyl function. A double carbonylation has been observed in the reaction of aryl halides with carbon monoxide and terminal alkenes which yields 4-arylfuranones such as (152). The proposed mechanism involves oxidative addition of the aryl halide to palladium and insertion of the carbon monoxide to give an acyl palladium species. This is followed by coordination and insertion of the alkene. A second carbon monoxide insertion is faster than -hydride elimination and, after intramolecular attack, leads to the product. The palladium-catalysed reaction of aryl iodides with simple ketones such as acetone in the presence of carbon monoxide has been shown to yield 1,3-diketones such as... 

The palladium-catalysed reaction of vinylic halides with alkenes to form carbonyl compounds can be useful synthetically. Acrolein acetals can act as substrates in the presence of amines to form dienals in protected form [equation (34)].Addition of terminal vinylic iodides to enones is also possible,... 

Muzart, J. (2005) Palladium-catalysed reactions of alcohols. Part D Rearrangements, carbonylations. 

Palladium salts are able to catalyse diyne carbonylation, so the reaction can be performed at room temperature under 1 atm of carbon monoxide. Thiourea (H2NCSNH2), which is added to stabilise the Pd catalyst (Scheme 34), is described as the best ligand for the efficiency of this reaction [124]. 

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],... 

Palladium-catalysed coupling reactions under carbon monoxide have been extensively used in traditional medicinal chemistry72. Despite this, these crucial transformations have hardly been employed in combinatorial chemistry. These shortcomings have recently been recognised and a series of microwave-heated carbonylative transformations with solid or liquid CO-sources have been reported. 

Kaiser, N.F.K., Hallberg, A. and Larhed, M In situ generation of carbon monoxide from solid molybdenum hexacarbonyl a convenient and fast route to palladium-catalysed carbonylation reactions, J. Comb. Chem., 2002, 4, 109-111. 

It is reported that the palladium-catalysed intramolecular aromatization of 1,1 -dichloro-9/T-fluoren-9-yIidene (15) may lead to the formation of fullerene fragments.89 The amiulation reaction, under palladium catalysis, between iodoanflines and ketones may yield indole derivatives.90 There have also been studies of the palladium-catalysed carbonylation of o-iodophenols with allenes which may lead to l-benzopyran-4-one derivatives,91 of the intramolecular coupling of phenols with aryl halides,92 and of the intramolecular Heck aiylation of cyclic enamides.93... 

Palladium-catalysed chemo- and enantio-selective oxidation of allylic esters and carbonates has been achieved using nitronates as nucleophilic oxidants. The products, o /3-unsaturalcd carbonyl compounds, were obtained in excellent yields and ees. The mechanism in Scheme 5 has been suggested for the reaction.108... 

The application of organozinc iodides prepared in THF is illustrated in Protocols 4 and 5, which describe the palladium catalysed cross-coupling of a serine-derived organozinc iodide with a vinyl iodide, and the palladium catalysed carbonylative cross-coupling of another serine-derived organozinc iodide with a functionalized aromatic iodide. In the reaction with the vinyl iodide, it is important to transfer the solution of the organozinc iodide from the residual zinc, since this can react unproductively with the electrophile. In the case of the carbonylative coupling with the functionalized aromatic iodide, such a transfer is unnecessary, since the zinc does not react with the electrophile under the reaction conditions. These two protocols also illustrate how to conduct such reactions on different scales. 

Nickel or palladium catalysed carbonyl addition and related reactions... 

Palladium-catalysed carbonylation of halides, with carbon monoxide, can be used to prepare esters, amides and ketones by trapping the intermediate acylpalladium halide with alcohols,amines and organometal-lics, respectively. Boronic acids are probably the best organometallics for the preparation of ketones, but conditions must be adjusted to give the best selectivity between the acylation reaction and simple Suzuki coupling of the boronic acid with the starting halide. ... 

Coupling reactions using orf/zo-haloanilines have been widely used in these instances no reductive step is required, though the carbonyl unit is sometimes incorporated in masked form requiring deprotection the examples shown are a palladium-catalysed coupling and a silyl ether/nitroarene condensation. ... 

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