Carbonyl addition palladium catalysed

The palladium-catalysed decarboxylative carbonylation of 5-vinyloxazolidin-2-ones 218 caused, unexpectedly, a ring enlargement process to 5-lactams 219 <00JA2944>. The conjugate addition of 4-phenyloxazolidin-2-one to a nitroalkene was used for the synthesis of diastereoisomers of dethiobiotin <00EJO3575>. Attempted deprotection of the O-TBDMS... 

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

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... 

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. 

Hydroxyalkenes possessing a nucleophilic group on C-5 cyclize, via palladium-catalysed addition of the nucleophile to the alkene and subsequent carbonylative lactonization to the 3-hydroxy-group, to give bicyclic [3-3-0] systems. This general process has been used to prepare bicyclic bis-lactones, cis-3-hydroxypyrrolidine-... 

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,... 

Palladium is a useful catalyst in several reactions which lead to keto-esters. p-Keto-esters react with allylic carbonates, with catalysis by palladium, in a decarboxylative allylation reaction. y-Keto-esters are prepared, in reasonable yield, by the palladium-catalysed regioselective oxidation of Py-unsaturated esters. y-Keto-esters are obtained in good yield by the palladium-catalysed Reformatsky reaction of ethyl bromoacetate and acid chlorides. Derivatives of y-ketopimelic acid are formed by the rhodium-carbonyl-catalysed reaction of derivatives of acrylic acid with carbon monoxide. A mild method for the conversion of propiolic esters into P-keto-esters via thiol addition has been reported (Scheme 63) it has been used in a formal synthesis of ( )-thienamycin. 

Addition of tributylstannyl-lithium to crotonaldehyde and protection of the resulting alcohol with chloromethyl methyl ether gives the stannane (192), which reacts with both alkyl and aryl aldehydes RCHO to form specifically the t/rr o-hydroxy-enol ethers (193). These latter compounds have been used to prepare tra/i5-4,5-disubstituted butyrolactones by hydrolysis and subsequent oxidation. Palladium-catalysed carbonylation of RX in the presence of organotin species constitutes a useful synthesis of unsymmetrical ketones, and in the example reported this year RX is an arenediazonium salt. The reaction, which is basically an aromatic acylation, proceeds in good to excellent yield. Another Pd-catalysed reaction of aromatics, this time aryl bromides, is their reaction with acetonyltributyltin (194), prepared from methoxytributyltin and isopropenyl acetate, to give the arylacetones (195). ... 

Collard, S. and Keep, A. (2003) Synthesis of 3-substituted isoindolin-l-ones via a palladium-catalysed 3-component carbonylation/amination/Michael addition process. Tetrahedron Letters, 44, 7441-7443. 

Air-stable palladium(O) catalyst, [(Cy3P)2Pd(H)(H20)]BF4, catalyses carbonylation of propargylic alcohols to generate dienoic acids and esters (equation 167)286. Since propar-gyl alcohols are obtained from carbonyl compounds by acetyhde addition reactions, this sequence constitutes a three-carbon homologation. a-Allenic alcohols are converted to tt-vinylacrylic acids under similar conditions (equation 168)287. 

The reductive elimination/oxidative addition is of practical importance in catalytic cycles, for example the rhodium/methyl iodide catalysed carbonylation of methanol. In organic synthesis the palladium or nickel catalysed cross-coupling presents a very common example involving oxidative addition and reductive elimination. A simplified scheme is shown in Figure 2.19 [17],... 

It is remarkable that the palladium(O) complexes are inactive in the absence of chloroform.236 Palladium acetate-bipyridine complex has been reported to catalyse conjugate addition of arylboronic acids to a -unsaturated carbonyl compounds in aqueous media with high yields.237... 

Palladium compounds will also catalyse the addition of hexamethylditin to terminal alkynes, or carbonyl-activated medial alkynes (e.g. equation 18-42),27 and tris(trimethyl-stannyl)ethene can be prepared by the addition of hexamethylditin to trimethyl-ethynyltin. Kt6Sn2 And Bu6Sn2 do not react under these conditions, but reaction does occur under high pressure (750 to 1300 MPa, 7.5 x 103 to 1.3 x 104 atm).55... 

The synthesis of polycyclic compounds can also be accomplished by a palladium(O)-catalysed transformation of enediynes [75]. In a process described by Negishi and coworkers, enetetraynes of type 132 undergo a tetracyclization followed by a carbonylative esterification to form the fifth ring leading to 133 in 66% yield. In this case, the initial alkenyl-palladium species is obtained by an oxidative addition of palladium(0) to the alkenyliodide moiety in 132 [76] (Scheme 8.34). 

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