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Palladium(II) acetate

About: Palladium(II) acetate is a(n) research topic. Over the lifetime, 561 publication(s) have been published within this topic receiving 19615 citation(s).

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TL;DR: P palladium acetate was found to be the most effective for the direct arylation of olefins with aromatic compounds in the presence of acetic acid.
Abstract: Olefins react with benzene derivatives to produce aryl-substituted olefins uia direct substitution of the aromatic compound for hydrogen on the double bond of the olefin in the presence of palladium salts and reduced palladium metal. The reaction may be made catalytic with respect to the palladium salts by using cupric acetate or silver acetate, and air as reoxidants. The reaction provides an extremely convenient method for the synthesis of a wide variety of olefinic compounds. xtensive studies on reactions of olefins in the presE ence of transition metal compounds have been carried out. Much less is known about arylation of olefins with transition metal compounds. Most recently, Heck described interesting arylation reactions of olefins with arylating agents such as arylmercuric halides in the presence of group VI11 metal salts, and showed that palladium salts are the most generally useful, with rhodium and ruthenium salts next best. We have reported a novel method of synthesizing stilbene derivatives by substitution of aromatic compounds for hydrogen on the double bond of the styrenepalladium chloride ~ o m p l e x . ~ In the course of our work, palladium acetate was found to be the most effective for the direct arylation of olefins with aromatic compounds in the presence of acetic acid. The present paper reports a study of substitution reaction of olefins with benzene derivatives by means of palladium salts, especially palladium acetate. A preliminary communication of a portion of this work has been given.4 ( I ) On leave of absence from Ube Industries, Ltd., Ube, Japan. (2) (a) R. F. Heck, J . Amer. Chem. Soc., 90, 5518 (1968); (b) R .F. Heck, ibid., 90, 5526 (1968); (c) R. F. Heck, ibid., 90, 5531 (1968); (d) R. F. Heck, ibid., 90, 5535 (1968); (e) R. F. Heck, ibid., 90, 5542 (1968). (3) (a) I. Moritani and Y. Fujiwara, Tefrahedron L e f f . , 1119 (1967); (b) Y . Fujiwara, I. Moritani, and M. Matsuda, Tetrahedron, 24, 4819 (1968). (4) Y. Fujiwara, I. Moritani, M. Matsuda, and S . Teranishi, Tetrahedron Lett., 633 (1968). Results and Discussion In previous papers3 we described our initial work on the reactions of the styrene-palladium(I1) chloride complex with benzene derivatives to give stilbenes. It was noted that for this arylation on a P-carbon atom of styrene, the presence of a carboxylic acid such as acetic is essential because the reactants form a homogeneous solution and the reaction proceeds best in this solvent. Further, it was found that when sodium acetate was added, the yield was greatly increased. Palladium(I1) acetate has been found to be the most generally useful, with palladium(I1) chloride-sodium acetate next best for the direct arylation of olefins with benzene derivatives. The aromatic substitution of olefins takes place in homogeneous solutions of reactant olefin and palladium(I1) acetate (equal mole equivalents to olefin) in a solution of the aromatic compound (large excess) and acetic acid. The solution is stirred in the presence of air for a few minutes to several hours (8 hr usually), to give from 10% to ca. 90% yield of arylated products, with reduced metallic palladium and a very small amount of acetates. With unsymmetrical olefins, the aryl group generally adds predominantly to the less substituted carbon atom of the double bond because of steric hindrance of the substituents. This is consistent with that observed in the Heck arylation.2 Although cis and trans mixtures are formed, no mixtures resulting from arylation in both directions to unsymmetrical olefins have been found. Increasing substitution on the olefinic carbons decreases the reactivity of the olefin in the palladium acetate arylation reaction. For example, the reaction of triphenylethylene with benzene and a palladium acetate catalyst gave tetraphenylethylene in low yield (13 %),5 while styrene reacts with benzene to afford trans-stilbene in almost quantitative yield. Results are given in Table I. (5) Yields of arylation products given in this paper are based on the amount of palladium salt utilized. Journal of the American Chemical Soc ie t y J 91:25 December 3, 1969

441 citations

Journal ArticleDOI
Abstract: (E,E) and (E,Z) conjugated dienoates, dienones and dienals are obtained with high stereospecificity (⩾95%) and in high yields from the corresponding (E) and (Z) vinylic halides and vinylic substrates (methyl acrylate, methyl vinyl ketone or acrolein), in the presence of potassium carbonate, tetrabutylammonium chloride and a catalytic amount of palladium acetate, in N,N-dimethylformamide at room temperature.

280 citations

Journal ArticleDOI
Abstract: Selective palladium-catalyzed aerobic conditions of olefins and conjugated dienes with the aid of a metal macrocycle-quinone system have been developed. This involves a multistep electron transfer with three catalysts (Pd(OAc){sub 2}, hydroquinone, metal macrocycle). The triple catalytic system was applied to (i) 1,4-oxidation of conjugated dienes (1,4-diacetoxylation and 1,4-dialkoxylation), (ii) oxidation of terminal olefins to ketones, and (iii) allylic oxidation of cyclic olefins to 2-alken-1-yl acetates. The reactions occur under very mild conditions, (i) and (ii) at room temperature and (iii) at 60{degree}C, and are reminiscent of aerobic processes occurring in living organisms. Thus, there is an electron transfer from the substrate to Pd(II) giving Pd(0), followed by another electron transfer from Pd(0) to benzoquinone. The hydroquinone thus formed transfers electrons to the oxidized form of the metal macrocycle, which is reduced.

264 citations

Journal ArticleDOI
Abstract: A number of 2,3-disubstituted 1-indenones have been prepared in fair to good yields by treating o-iodo- or o-bromobenzaldehyde with various internal alkynes in the presence of a palladium catalyst. Synthetically, the methodology provides an especially convenient route to stable hindered indenones containing aryl, silyl, and tert-alkyl groups. The reaction is believed to proceed through a palladium-(IV) intermediate, and the regiochemistry of the reaction is controlled sterically

238 citations

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