Palladium carbonyl chloride

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. 

Palladium alkoxide complexes are thought to be formed in the reactions of alcohols catalyzed by palladium(II) chloride. These reactions include the oxidation of alcohols, yielding acetals or ketones,137,138 and their carbonylation, yielding esters.139 Alkoxide intermediates are also thought to be involved in the reaction of sulfur dioxide with [PdCl2] suspended in alcohol (equation 15).140,141... 

The synthesis of succinic acid derivatives, /3-alkoxy esters, and a,j3-unsaturated esters from olefins by palladium catalyzed carbonylation reactions in alcohol have been reported (24, 25, 26, 27), but full experimental details of the syntheses are incomplete and in most cases the yields of yS-alkoxy ester and diester products are low. A similar reaction employing stoichiometric amounts of palladium (II) has also been reported (28). In order to explore the scope of this reaction for the syntheses of yS-alkoxy esters and succinic acid derivatives, representative cyclic and acyclic olefins were carbonylated under these same conditions (Table I). The reactions were carried out in methanol at room temperature using catalytic amounts of palladium (II) chloride and stoichiometric amounts of copper (II) chloride under 2 atm of carbon monoxide. The methoxypalladation reaction of 1-pentene affords a good conversion (55% ) of olefin to methyl 3-methoxyhexanoate, the product of Markov-nikov addition. In the carbonylation of other 1-olefins, f3-methoxy methyl esters were obtained in high yields however, substitution of a methyl group on the double bond reduced the yield of ester markedly. For example, the carbonylation of 2-methyl-l-butene afforded < 10% yield of methyl 3-methyl-3-methoxypentanoate. This suggests that unsubstituted 1-olefins may be preferentially carbonylated in the presence of substituted 1-olefins or internal olefins. The reactivities of the olefins fall in the order RCH =CHo ]> ci -RCH=CHR > trans-RCH =CHR >... 

Di-jjL-carbonylhexacarbonyldicobalt, 99 Dichlorobis(triphenylphosphine)palla-dium(II), 103 Iron carbonyl, 152 Palladium(II) chloride-Copper(II) chloride, 235... 

Terminal alkenes could be efficiently aminated by nonhindered secondary amines in a process requiring 1 equiv. of palladium(II) chloride, 3 equiv. of amine and a reduction at temperatures below -20 C (path a, Scheme 5) 21,22 however, primary amines and/or internal alkenes were less efficient, producing only 40-50% yields of amination product. Oxidative cleavage of the unstable o-alkylpalladium(II) in the presence of a nucleophile resulted in vicinal oxamination or diamination of the alkene (path b).23,24 Car-bonylation resulted in the isolation of stable o-acylpalladium(II) species (path c),23 which were oxidatively cleaved to give 3-amino esters (path d)26 or further carbonylated to give y-amino-a-ketoamidei (path e).27... 

The initial synthetic approach to conivaptan HCl (1) employed by the Yamanouchi discovery group26 commenced with commercially available benzazepinone 10. Acylation of 10 with p-nitrobenzoyl chloride provided benzamide 11. Subsequent hydrogenation of 11 over palladium on carbon yielded aniline 12, which was in turn condensed with biphenyl-2-carbonyl chloride to provide bis(amide) 13. Bis(amide) 13 was subsequently heated with copper(II) bromide in boiling chloroform/ethyl acetate to furnish a-bromoketone 14. It is interesting that condensation of a-bromoketone 14 with acetamidine hydrochloride in the presence of potassium carbonate in boiling acetonitrile afforded not only the desired imidazobenzazepine product (1 53% yield, 2 steps) but also the related oxazolobenzazepine 15 (7% yield, 2 steps), which presumably resulted from nucleophilic attack of the benzazepinone oxygen on the amidine moiety followed by loss of ammonia. Separation of oxazolobenzazepine byproduct 15 from imidazobenzazepine 1 by silica gel chromatography followed by treatment of the purified imidazobenzazepine free-base with hydrochloric acid then provided conivaptan HCl (1). 

The condensation of aromatic compounds with tellurium tetrachloride produces aryl tellurium trichlorides that can be converted to diaryl ditelluriums, which, in turn, can be reduced to arenetellurols. These tellurols condense with alkyl halides to give aryl alkyl telluriums. When these aryl alkyl telluriums are carbonylated with carbon monoxide in the presence of palladium(II) chloride or acetate, arenecarboxylic acids are formed1-4... 

The addition of sodium benzenetellurolate to 3-hydroxy-l-propynes produces (Z)-2-hydroxyalkylethenyl phenyl telluriums. These compounds treated with carbon monoxide in dichloromethane in the presence of stoichiometric amounts of triethylamine and palladium(II) chloride are carbonylated and the resulting acids converted to lactones1. 

The carbonylations also proceed with palladium(II) acetate instead of palladium(II) chloride. When the carbonylation reactions are carried out with methanol as the reaction medium methyl benzoates are obtained. ... 

Olefins are usually carbonylated in the presence of metal carbonyls, such as nickel, cobalt, and iron carbonyls under homogeneous conditions, and the mechanism of these carbonylations has been established in several cases. On the other hand, isolation or formation of true palladium carbonyl has not been reported. Since palladium is an efficient and versatile catalyst for various types of the carbonylation mentioned above, the mechanisms of the carbonylation of olefin-palladium chloride complexes and of metallic palladium catalyzed carbonylations seem to be worth investigating. 

CARBONYLATION Dicarbonylbisltri-phenylphosphine)nickel. Palladium(II) acetate. Palladium(II) chloride. 

Surprisingly, palladium(II) salts supported on NaY zeolite produce DMC, even without halogens. The preferred support seems to be active carbon compared to zeolites because of higher DMC selectivities based on both MN and carbon monoxide, >95% in the case of active carbon and 80-90% in the case of zeolites. Palladium chloride/copper chloride on active carbon is likely used as a catalytic system in the industrial process. Because the carbonylation of MN to DMC occurs without water coproduction, the use of palladium salts as catalysts does not adversely affect selectivity. In the carbonylation reactor outlet some amount of methyl-chloroformate is present, as expected because it is known that palladium(II) chloride supported on alumina or silica catalyzes the reaction between MN, CO, and HCl to give methylchloroformate. " The presence of halide ions in the catalytic system and the methylchloroformate generation likely raise some corrosiveness issues. 

Carbonylation of organoboranes Carbon monoxide. N,N -Carbonyl-diimidazole. 2,3-Dimethyl-2-butylborane. Hydrogen fluoride—Antimony pentafluoride. Lithium trimethoxyaluminum hydride. Palladium (II) chloride. 

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. 

Anstatt Palladium(II)-chlorid kann auch Palladium(II)-acetat oder Octacarbonyl-dikobalt ver-wendet werden. Beim Einsalz von Carbonyl-metall-Verbindungen zeigt sich jedoch, daB nur beim Kobalt RingschluB eintritt, wahrend Eisen-, Nickel- oder Molybdan-Carbonyl-Verbin-dungen zwar Komplexe bilden, aber keine Cyclisierung bewirken333. 

A-Alkylphenotellurazines form 1 1 molecular complexes with mercury(II) halides and with silver nitrate or silver perchlorate <85KGS757>. Bis(benzonitrile)palladium(II) chloride reacts to form a 2 1 adduct and rhodium carbonyls also complex with phenotellurazines <82D0K(266)1164>. 

Palladium(II) chloride-copper(Il) chloride-carbon monoxide. 13, 235-236 Oxidative carbonylation. This combination of reagents is commonly used for homologation of alkynes. The products are usually obtained as the methyl esters. Heterocyclization attends C-C bond formation when a proper functional group is present at a short distance. 

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) ... 

A process has been suggested that uses carbon monoxide, an aromatic dichloride and a diamine. As catalyst, a palladium complex is used, bis(triphenylphosphine)palladium(II)chloride. The catalyst induces the carbonylation of aryl aromatic chlorides. 

Deoxymannojirimycin has been synthesized with excellent diastereoselec-tivity in a process based upon a palladium(II)-catalysed cyclization of an allylic alcohol 62 derived from D-mannitol. C-6 Homologues of 1-deoxynojirimycin and 1-deoxy-L-idonojirimycin (l,5,6-trideoxy-l,5-imino-D-gf/Mco- and -h-ido-heptitols) have also been prepared using palladium chemistry. In these reports the protected aminohex-l-enitol 63, derived from methyl a-D-glucopyranoside, was amino-carbonylated in the presence of palladium(II) chloride to afford a mixture of cyclized products whose composition was dependent upon the reaction conditions utilized. Two of these products, 64 and 65, were reductively transformed into the DNJ and 1-deoxy-L-idonojirimydn homolgues respectively 58,59... 

Palladium-carbonyl complexes are typically formed from PdX2 (X = Cl, Br, or I) and CO. For example, Pd2(CO)2Cl4 is obtained by high-pressure carbonylation of PdCl2. Similarly, the anionic M[Pd(CO)X3] are obtained from carbonylation of PdX2 or M2(Pd2X6). While the iodide is relatively unstable, the chloride and bromide could be characterized by X-ray crystallography. 

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