Palladium copper catalyst

Tributylstannyl)-3-cyclobutene-1,2-diones and 4-methyl-3-(tributylstan-nyl)-3-cyclobutene-l,2-dione 2-ethylene acetals undergo the palladium/copper-catalyzed cross coupling with acyl halides, and palladium-catalyzed carbon-ylative cross coupling with aryl/heteroaryl iodides [45]. The coupling reaction of alkenyl (phenyl )iodonium triflates is also performed by a palladium/copper catalyst [46],... 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

Scope of this synthetic strategy is not limited to benzofiirans. The reaction of 2-iodo-3-hydroxypyridine and 1,1 -diethoxy-2-propync under Sonogashira coupling conditions (palladium-copper catalyst system) leads to the formation of the substituted furo[3,2-6]pyridine shown in 3.56.72... 

Terminal alkenes can be selectively oxidized to aldehydes by reaction with oxygen, using a palladium-copper catalyst in tertiary butanol (equation 35)160. This reaction is contrary to the normal oxidation process which yields a ketone as the major product. The palladium(II) oxidation of terminal alkenes to give methyl ketones is known as the Wacker process. It is a very well established reaction in both laboratory and industrial synthesis161162. The Wacker oxidation of alkenes has been used in the key step in the synthesis of the male sex pheromone of Hylotrupes bajulus (equation 36)163. 

A variation of this reaction uses a palladium-copper catalyst on MontmoriUonite clay. When aniline reacted with methyl acrylate in acetic acid and the Pd-Cu-Mon-tmorillonite KIO, PhCH=CHC02Me was obtained. ... 

Hattori, T. Kijima, M. Shirakawa, H. Oxidative polycondensation of acetylene by iodine in the presence of palladium-copper catalyst. Synth. Met. 1997, 84, 357-358. 

Simple preparation of bimetallic palladium-copper catalysts for selective liquid phase semihydrogenation of functionahzed acetylenes and propargylic alcohols... 

To test the selectivity of the bimetallic system, monosubstituted acetylenes (Table I) and disubstituted acetylenes (Table II) were hydrogenated with the use of the silica supported palladium-copper catalysts. The yields of the olefins at 100% conversion of the acetylene are given. However, in all cases with longer hydrogenation times it was possible to end up with the fully saturated product. 

The method described allows fast and consistent production of silica supported bimetallic palladium-copper catalysts in the liquid phase at room temperature, without the need for high temperature reduction. The catalysts show homogeneous dispersion of the mixed metal particles over the support surface and are ready to use immediately after preparation. 

The silica supported palladium-copper catalysts are selective in the hydrogenation of monosubstituted acetylenes giving high yields of either olefins or saturated hydrocarbons, depending on the reaction time. In addition, the catalytic system shows reasonable selectivity towards cis-olefins in the hydrogenation of disubstituted acetylenes. 

These processes that substitute carbon monoxide, oxygen, and an alcohol for phosgene appear to be on the verge of commercial viability. There may be questions of catalyst life and recyclability that are not mentioned in the papers and patents. Some reaction times need to be shortened through the use of improved catalysts. Aresta et. al do say that their palladium-copper catalyst system can be recycled.46 The use of supported catalysts that could be recovered by filtration could simplify workups and recycling. (Supported catalysts are described in Chap. 5.)... 

Lewis, L.S., A.B. Norman, and A. Robinson The evaluation of palladium/copper catalysts for CO removal ... 

OXIDATION OF OLEFINS TO ALDEHYDES USING A PALLADIUM-COPPER CATALYST... 

Acetaldehyde (CH3CH=0) boils close to room temperature (bp 20°C). It is manufactured mainly by the oxidation of ethylene over a palladium-copper catalyst, and about 1 billion pounds are produced worldwide each year. 

The use of the palladium-copper catalyst enables the cyclization of compound 125d under milder conditions, which leads to the retention of the chlorine atom in the molecule. Owing to the presence of aryl iodides (bromides) in the reaction mixture, quinoxaline 125d converts into 1-benzyl-substituted imidazo[l,2-a]quinoxalines 127a-g in one-pot process. The use of iodine analogs instead of bromonitroben-zenes allows one to increase the yield of compounds 127a, b by 20 % (Bakherad et al. 2012). 

PREPARATION OF PALLADIUM-COPPER CATALYSTS OF DESIGNED SURFACE STRUCTURE ZS. BOON/JR, T. MALLAT, S. SZABI and J. PETRd ... 

---