Arenes Palladium chloride

The above reagents (ok the safrole and H2O aren t reagent) are weighed or measured accordingly. The flask is securely clamped into place on the magnetic stirrer. Add the DMF and H2O. Start stirring, and then slowly add the palladium chloride and cuprous chloride. If you add the powders first then the liquids you ll have problems with the stir bar finding a place to spin. 

Arene(tricarbonyl)chromium complexes, 19 Nickel boride, 197 to trans-alkenes Chromium(II) sulfate, 84 of anhydrides to lactones Tetrachlorotris[bis(l,4-diphenyl-phosphine)butane]diruthenium, 288 of aromatic rings Palladium catalysts, 230 Raney nickel, 265 Sodium borohydride-1,3-Dicyano-benzene, 279 of aryl halides to arenes Palladium on carbon, 230 of benzyl ethers to alcohols Palladium catalysts, 230 of carboxylic acids to aldehydes Vilsmeier reagent, 341 of epoxides to alcohols Samarium(II) iodide, 270 Sodium hydride-Sodium /-amyloxide-Nickel(II) chloride, 281 Sodium hydride-Sodium /-amyloxide-Zinc chloride, 281 of esters to alcohols Sodium borohydride, 278 of imines and related compounds Arene(tricarbonyl)chromium complexes, 19... 

Palladation of an arene is a very facile reaction when, before the C-H activation step, coordination of palladium to a nearby ligand functionality in the molecule occurs. The first report of a stoichiometric intramolecular palladation is probably the reaction of diazobenzene and palladium chloride by Cope in 1967 [6a], Intramolecular palladation is a widespread reaction that has often been used as a starting point for synthesizing new molecules using insertion reactions in the arylpal-... 

Dehalogenation of chlorinated arenes. Palladium (10%) on carbon catalyzes the rapid transfer of hydrogen from ammonium formate to aryl chlorides to provide the parent arene. Dehalogenation of 2,4,6-trichlorophenol proceeds through di-chloro- and chlorophenol and is complete within 10 minutes at ambient temperature and pressure. 

The acylation of arenes with alcohols has been shown to be possible using a palladium chloride catalyst in the presence of f-butylhydroperoxide. In 2-arylpyridines, substitution is directed to the ortho-position and, after initial paUadation, the formation of intermediate (59) is likely before reductive elimination yields the acylated product. The regioselective acetoxylation of indoles, at the 3-position, has been achieved using the palladium-catalysed reaction with phenyliodonium acetate. 3-Acyl indoles may also be prepared using acetyl chlorides with zirconium tetrachloride as a Lewis acid catalyst. 

Several studies have used palladium catalysis in the arylation of benzoxazoles. A palladium catalyst with a phosphine ligand allows their reaction with aryl mesylates without the requirement for acid or copper additives. In the reaction with arene-sulfonyl chloride, palladium is used in combination with copper. A plausible mechanism involves initial cupration of the benzoxazole followed by copper—palladium exchange and oxidative addition of the sulfonyl chloride to palladium to give (84). This intermediate may lose sulfur dioxide to give an aryl palladium species, which, on reductive elimination, yields 2-arylbenzoxazole. The arylation of benzoxazoles and benzthiazoles with aryl boronic acids is also catalysed by a combination of palladium... 

Other highly active palladium chloride-based catalysts include di-2-pyridylmethylamine-based paUadium, tr(WM-bidentate pyridine, and PdCl2/phosphinous acid complexes. Typical examples are shown in Scheme 2. This section is concerned with the coupling reactions of aryl chlorides using the above PdCh-based catalysts. Chloro arenes are cheap to manufacture and therefore play a vital role as intermediates in the chemical industry. The low reactivity of chlorides is usually attributed to the strength of the C-Cl bond. Remarkable progress has been achieved since 1998 in the development of palladium-based catalysts that can in fact accomplish cross-couplings and Heck reactions. ... 

Fagnou and co-workers reported on the use of a palladium source in the presence of different phosphine ligands for the intramolecular direct arylation reaction of arenes with bromides [56]. Later, they discovered that new conditions employing palladium complex 27 promoted the direct arylation of a broad range of aryl chlorides to form six- and five-membered ring biaryls including different functionalities as ether, amine, amide and alkyl (Scheme 7.11) [57]. 

The synthesis of the second Stille coupling partner 34 was efficiently achieved in three steps. First, 2-bromojuglone (36) [28] was protected as its methoxymethyl ether (46, Scheme 3.7). The quinone was reduced using sodium thiosulfate, and the resulting hydroquinone was protected with methoxymethyl chloride to afford the arene 47. Finally, stannylation using tetrakis-(triphenylphosphine)palladium and hexabutylditin [29] afforded the cross-coupling partner 34 in high yield. 

Perhaps the most industrially feasible approach has been developed by Rich and co-workers at General Electric, a palladium-catalyzed silylative decarbonylation reaction of aromatic acid chlorides with disilanes [Eq. (35)].97 One of the silicon centers from the disilane is transferred to the arene whereas the other acts as a chloride acceptor to produce the chlorosi-... 

The oxidative carbonylation of arenes to aromatic acids is a useful reaction which can be performed in the presence of Wacker-type palladium catalysts (equation 176). The stoichiometric reaction of Pd(OAc)2 with various aromatic compounds such as benzene, toluene or anisole at 100 °C in the presence of CO gives aromatic acids in low to fair yields.446 This reaction is thought to proceed via CO insertion between a palladium-carbon (arene) allyl chloride, but substantial amounts of phenol and coupling by-products are formed.447... 

As can be seen in the scheme below, a series of substituted 2-(2-aminothiazol-4-yl)-benzo[ ]furans with inhibitory activity for leukotriene B4 were made from benzofurans via acylation, followed by Hantzsch thiazole formation <070BC3083>. 2-Substituted benzo[ ]furans could also be generated via an aerobic oxidative coupling of 2-unsubstituted benzo[ ]furans with arenes through the palladium-catalyzed double C-H activation <07OL3137>. In addition, 2,3-diarylbenzo h I uran could be constructed by a palladium-catalyzed arylation of benzo[6]furan with an aryl chloride in the presence of a bulky, and electron-rich phosphine <07OL1449>. 

A variety of arenes and heteroarenes react with alkenes in the presence of palladium(II) derivatives to produce alkenyl substitution products. Three methods are commonly employed for the in situ preparation of palladium derivatives (i) direct metallation of an arene or heteroarene with a Pd(II) salt (ii) exchange of the organic group from a main-group organometallic to a Pd(II) compound (iii) oxidative addition of an organic halide, an acetate, or triflate salt to Pd(0) or a Pd(0) complex. For catalytic reactions Cu(II) chloride or p-benzoquinone is usually used to reoxidize Pd(0) to Pd(II). 

J. G. Verkade has synthesized a series of bicyclic triamino phosphines that are potent a-donors to palladium, yet can be modified to incorporate a variety of steric encumberance.46 It was found that ligand L13 could promote the catalytic amination of both aryl chlorides and bromides with secondary cyclic amines and anilines. L13 was not as effective for aliphatic secondary acyclic amines and primary aliphatic amines. The scope was improved with ligand L14, but as with other third generation ligands, primary aliphatic amines were prone to giving de-halogenated arene. 

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