Aromatic Metalation Reactions by Palladium(II) and Platinum(II) on Aromatic Aldoximes and Ketoximes
01 Nov 1970-Bulletin of the Chemical Society of Japan (The Chemical Society of Japan 公益社団法人 日本化学会)-Vol. 43, Iss: 11, pp 3480-3485
TL;DR: Ortho metalation by palladium was observed in the reaction of lithium tetrachloropalladate(II) with various aromatic aldoximes and ketoximes in methanol in the presence of sodium acetate.
Abstract: Ortho metalation by palladium(II) was observed in the reaction of lithium tetrachloropalladate(II) with various aromatic aldoximes and ketoximes in methanol in the presence of sodium acetate. The obtained chloro-bridged complexes(7) possessed both ortho-attached palladiumcarbon σ-bonding and palladium-nitrogen coordinate bonding to oximes. Reactions of O-acyl and O-methyl oximes with lithium tetrachloropalladate(II) were also carried out. An ortho metalation was observed in the former case, but dichlorobis(O-methyl oxime)palladium(II) type complexes containing no palladium-carbon σ-bonds were predominantly formed in the latter case. The bridge-splitting reaction of chloro-bridged complexes with triphenylphosphine and the metathetic reaction with sodium bromide in acetone were carried out. In the case of potassium tetrachloroplatinate(II), an ortho metalation reaction was observed giving the complexes(10) but chloro-bridged complexes could not be isolated.
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TL;DR: In this article, the factors influencing the ease and mode of the reactions involving the direct intramolecular cyclopalladation of organic ligands at sp2- and sp3-carbon atoms are analysed and the principal requirements which must be met by the structure of the ligand, the characteristic features of the coordination intermediates, and the experimental reaction conditions are considered.
Abstract: The factors influencing the ease and mode of the reactions involving the direct intramolecular cyclopalladation of organic ligands at sp2- and sp3-carbon atoms are analysed and the principal requirements which must be met by the structure of the ligand, the characteristic features of the coordination intermediates, and the experimental reaction conditions are considered. The bibliography includes 232 references.
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TL;DR: In this article, the structures of N-phenylbenzaldimine with palladium(II) acetate in boiling acetic acid have been confirmed by IR and proton NMR data, which are different from those reported by Molnar and Orchin.
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TL;DR: Oxime palladacycles are thermally stable complexes not sensitive to air or moisture, easily prepared from very cheap materials, which can be used as versatile and very efficient catalysts for different carbon-carbon bond-forming reactions.
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TL;DR: Oxime-derived chloro-bridged palladacycles 12 and 13 are efficient complexes for the Suzuki-Miyaura reactions of aryl-, allyl-, and benzyl halides with aryalboronic acids, showing good turnover numbers and turnover frequencies under aerobic conditions.
Abstract: Oxime-derived chloro-bridged palladacycles 12 and 13 are efficient complexes for the Suzuki−Miyaura reactions of aryl-, allyl-, and benzyl halides with arylboronic acids. The isolated catalysts are thermally stable, not sensitive to air or moisture, and easily accessible from inexpensive starting materials. The reaction can be performed under aerobic conditions with aryl bromides and chlorides, displaying turnover numbers (TON) of up to 5 × 105 and turnover frequencies (TOF) of up to 198 000 h-1 for aryl bromides. Aryl chlorides undergo the Suzuki reaction with arylboronic acids with TON of up to 4700 and TOF up to 4700 h-1. Even inexpensive and readily available benzyl and allyl chlorides undergo the coupling reaction with good turnover numbers. Complexes of 12 catalyze the syntheses of symmetrical biaryls in good yields via reductive coupling of iodoarenes in the presence of Hunig's base.
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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
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