Palladium carbonate

Diacetone-L-sorbose (DAS) is oxidized at elevated temperatures in dilute sodium hydroxide in the presence of a catalyst (nickel chloride for bleach or palladium on carbon for air) or by electrolytic methods. After completion of the reaction, the mixture is worked up by acidification to 2,3 4,6-bis-0-isoptopyhdene-2-oxo-L-gulonic acid (2,3 4,6-diacetone-2-keto-L-gulonic acid) (DAG), which is isolated through filtration, washing, and drying. With sodium hypochlorite/nickel chloride, the reported DAG yields ate >90% (65). The oxidation with air has been reported, and a practical process was developed with palladium—carbon or platinum—carbon as catalyst (66,67). The electrolytic oxidation with nickel salts as the catalyst has also... 

Reduction of the halogen substituent has been carried out by different procedures such as catalytic hydrogenation using palladium-carbon or Raney nickel, red phosphorus and hydroiodic acid, and zinc and sulfuric acid (66AHQ6)347). 3-Deuteropyrazole has been... 

A mixture of 2.0 g (0.064 mol) of 2-fluoromethyl-3-(o-tolyl)-6-nitro-4(3H)-qulnazolinone, Oi g of 5% palladium-carbon and 100 ml of acetic acid is shaken for 30 minutes in hydrogen gas. The initial pressure of hydrogen gas is adjusted to 46 lb and the mixture is heated with an infrared lamp during the reaction. After 30 minutes of this reaction, the pressure of hydrogen gas decreases to 6 lb. After the mixture is cooled, the mixture is filtered to remove the catalyst. The filtrate is evaporated to remove acetic acid, and the residue is dissolved in chloroform. The chloroform solution is washed with 5% aqueous sodium hydroxide and water, successively. Then, the solution is dried and evaporated to remove solvent. The oily residue thus obtained is dissolved in 2 ml of chloroform, and the chloroform solution is passed through a column of 200 g of silica gel. The silica gel column is eluted with ethyl acetate-benzene (1 1). Then, the eluate is evaporated to remove solvent. The crude crystal obtained is washed with isopropylether and recrystallized from isopropanol. 0.95 g of 2-fluoromethyl-3-(o-tolyl)-6-amino-4(3H)-quinazolinone Is obtained. Yield 52.5% MP 195°-196°C. 

A mixture of 53.5 g (0.5 mol) of cyclopentylideneacetonitrile dissolved in 50 cc of absolute ethanol and 0.5 g of a palladium-carbon catalyst is hydrogenated with hydrogen at a pressure of about 40 lb for about 3 hours. An additional amount of 0.8 g of palladium-carbon catalyst is then added and the hydrogenation continued for about 4 hours during which time the reduction is substantially completed and the cyclopentylideneacetonitrile is converted to cyclopentylacetonitrile. The reaction mixture is filtered to remove the catalyst and the alcohol is evaporated in vacuo. 

Then 21.89 g of the hydrochloride salt was dissolved in 600 ml of 80% aqueous ethanol. With the addition of a palladium carbon catalyst, this solution was hydrogenated at room temperature under a hydrogen pressure of about 1.1 atmospheres. After 2 mols hydrogen had been absorbed, the catalyst was filtered off and the filtrate was evaporated in vacuo until crystallization occurred. Then the crystals were dissolved by heating in the smallest possible quantity of water and after cooling, the crystallized substance was filtered off, washed with water and dried in vacuo. The yield was 6.80 g, i.e., 39% of the theoretically possible yield. The resultant product recrystallized from water melted at 203° to 204°C. 

Formic acid at 98% had to be used as a solvent during a catalytic hydrogenation by using the palladium/carbon system. When the solvent came into contact with the catalyst there was a release of hydrogen. Does this accident result from the acid decomposition catalysed by palladium In this case the decomposition... 

Palladium/charcoal also could serve as a catalyst for Sonogashira reactions of peptides in aqueous media. Recently, Granja et al. used palladium/carbon associated with 4-diphenylphosphinobenzoic acid (4-DPPBA) or triphenylphosphine ligand to catalyze such a reaction in aqueous DMF (Eq. 4.16).34... 

The problems associated with the in situ approaches can be avoided by using a discrete catalyst. The presumed structure of the monometallic palladium catalyst contains the sulfonated phosphine ligand chelated to the palladium and a palladium-carbon bond (polymer), most probably in cis geometry with respect to the phosphorous (Fig. 8). 

It contains a palladium-carbon o-bond (alkyl or aryl)... 

As mentioned above nonconjugated dienes give stable complexes where the two double bonds can form a chelate complex. A common pathway in palladium-catalyzed oxidation of nonconjugated dienes is that, after a first nucleophilic addition to one of the double bonds, the second double bond inserts into the palladium-carbon bond. The new (cr-alkyl)palladium complex produced can then undergo a /(-elimination or an oxidative cleavage reaction (Scheme 2). An early example of this type of reaction, although not catalytic, was reported by Tsuji and Takahashi (equation 2)12. 

The use of 1,6-diene systems usually does not result in cyclization reactions with palladium ) salts. For example, with 1,6-heptadiene a /i-elimination takes place from the cqjr-intermediate to give diene 22 as the major product (equation 10)27. However, more recently Trost and Burgess21 have shown that with a 4,4-bis(phenylsulfonyl) derivative of 1,6-heptadiene (23) an insertion takes place to give a 5-membered ring product (24, equation 11). The final step of the latter reaction is oxidative cleavage of the palladium-carbon bond by CuCl2 to produce a carbon-chlorine bond. 

An example of an intramolecular palladium-catalyzed oxidation of an allene involving carbonylation was used in the synthesis of pumilotoxin 251 D (equation 32)65. Intramolecular aminopalladation of the allene followed by carbonylation of the palladium-carbon bond and subsequent oxidative cleavage of the acylpalladium intermediate by CuCE afforded pyrrolidine 72 in which the chirality at the carbon at the 2-position was established. 

The catalytic cycle proposed for the cyclization-hydrosilylation with the cationic palladium catalyst is classified into the type D in Scheme 2. The reaction consists of an olefin insertion into palladium-silicon bond and the metathesis between palladium-carbon and hydrogen-silicon bond, regenerating the silylpalladium intermediate and releasing the product where migratory insertion of the pendant olefin into the alkylpalladium is involved before the metathesis (Scheme 26).83a... 

A4 carene can also be obtained from A3 carene as follows (JCS (C) 46(1966)) Dissolve 1 g A3 carene in 50 ml propionic acid and heat at a suitable temperature (e.g., one-half hour at room temperature may do) in presence of /2g Palladium-Carbon catalyst (5%) in ethanol and filter, evaporate in vacuum (can distill 63.5/19.5). See J.Soc. Cosmet. Chem. 22,249(1971) for a review of (+) A3 carene chemistry. 

Add a 1 M excess of nitroethylene dropwise to liquid 5-benzyloxyindole (or other indole) on a steam bath over two hours. Cool, filter and recrystallize from methylene chloride-petroleum ether. Hydrogenate at two atmospheres over 10% palladium-carbon... 

DMA in 500 ml ether mix rapidly with 270 ml 0.9 M phenyl-Li, boil fifteen hours and extract as for (VI) or as described previously to get 8 g oily 4-methoxy-indoline (or its 1-methyl derivative) (VII). Alternatively, add 36 g naphthalene to 300 ml tetrahydrofuran and add 11 g Na metal cut in small pieces. Reflux and stir three hours and add 18 g (VI) and 8 g DEA in 200 ml tetrahydrofuran rapidly and boil twelve hours. Evaporate in vacuum, dissolve the oily residue in 2N HCI and extract with ether. Proceed as described to get (VII). 4 g (VII) in 200 ml dry pyridine add to 6 g Cu chloride in 400 ml pyridine and reflux 1 xh hours. Pour on water and extract with ether. Wash extract with 4N HCI and then water and dry and evaporate in vacuum the ether to get 2 g of the indole (VIII). Alternatively, dissolve 4 g (VII) and 9.5 g cinnamic acid in 700 ml mesitylene, add 1 g 5% palladium-carbon and reflux five hours. Filter, wash with HCI and NaHC03 and dry and evaporate in vacuum the mesitylene to get the red, oily (VIII) (can chromatograph on alumina and elute with benzene-petroleum ether). 

Formic acid, Palladium-carbon catalyst, 0418 Formic acid, Phosphorus pentaoxide, 0418 Furan-2-amidoxime, 1872... 

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