Ichiro Moritani

Aromatic substitution of olefins. VI. Arylation of olefins with palladium(II) acetate

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

ortho-Metalation reactions of N-phenylbenzaldimine and its related compounds by palladium(II) acetate

Abstract Di-μ-acetatobis(2,N-dihapto-N-phenylbenzaldimine)dipalladium(II) and related complexes have been prepared by the reaction of N-phenylbenzaldimine or related compounds with palladium(II) acetate in boiling acetic acid. Their halogen-bridged analogues have also been prepared by metathetical reactions with sodium chloride or bromide. The present compounds, the structures of which have been confirmed by IR and proton NMR data, are different from those reported by Molnar and Orchin. Reactions of chloro-bridged complexes with triphenylphosphine, pyridine and thallium acetylacetonate have also been carried out.

The reaction of σ-vinylpalladium complexes with alkyllithiums. Stereospecific syntheses of olefins from vinyl halides and alkyllithiums

Abstract Vinyl halides react with alkyllithium compounds in the presence of tetrakis(triphenylphosphine)palladium to give olefins stereospecifically in excellent or fairly good yields. When less reactive Grignard reagents are employed instead of alkyllithium compounds, these reactions can be carried out catalytically with palladium.

Reactions of ferrocenylcarbene IV. The synthesis of [3]-ferrocenophan-2-one tosylhydrazone and the thermal decomposition of its sodium salt☆

Abstract A practical synthesis of 1,1′-ferrocenediacetic acid (Va), the starting material for the preparation of [3]-ferrocenophan-2-one (VI) has been accomplished by successive reactions starting from l,l′-ferrocenedicarboxylic acid (IIIa). The synthesis of the tosylhydrazone (VII) and thermal decomposition of its sodium salt have been described. Ferrocenophane-β-carbene generated in the thermal decomposition has been suggested to be triplet.

Aromatic substitution of olefin—III : Reaction of styrene-palladium(II) chloride complex

Abstract trans-Stilbene derivatives have been obtained from a reaction of styrene-palladium (II) complex (1) with aromatic compounds in the presence of carboxylic acids. This novel method of synthesizing stilbene derivatives by substitution of an H atom on the double bond of the styrene of complex 1 is the first case of aromatic substitution of olefins. In a typical reaction, the complex 1 with benzene and acetic acid afforded trans-stilbene in a 26 % yield and a saturated acetate (13 %), and when sodium acetate was added, the yield was surprisingly increaased.

Dibenzo[a.d]cycloheptenylidene and tribenzo[a,c,e]cycloheptenylidene : Stereochemistry of the addition reaction

Abstract Photolysis of 5-diazo[a,d]cycloheptene ( 10 ) and 9-diazotribenzo[a,c,e]cycloheptene ( 23 ) in cis and trans -2-butene led stereospecifically to the formation of cyclopropane derivatives. Nonstereospecific addition of dibenzo[a,d]cycloheptenylidene could not be detected by carrying out the photolysis in a large excess of cyclohexane, or by photosensitized decomposition of 10 . It is concluded that photolysis of 10 leads to a singlet ( 6 ) which converts to the triplet state and reacts stereospecically with olefins to form cyclopropanes. These stereochemical results were reasonably explained by considering that a charge transfer complex plays an important role in the transition state of the addition reaction of 6 to olefins. The electronic structures of these carbenes are discussed in the light of results obtained from ESR and optical spectroscopy.

Aromatic substitution of olefin—VII : Reactions of lower olefins with benzene by palladium acetate☆

Abstract The phenylation of propylene, 1-butene, rans- and cis-butenes, and 1,3-butadiene with benzene was carried out in the presence of palladium acetate and acetic acid. It was concluded that, although the usual olefins predominantly undergo phenylation, an olefin which can easily form a π-allyl complex gives acetates as major products under the present reaction conditions.Abstract The phenylation of propylene, 1-butene, rans - and cis -butenes, and 1,3-butadiene with benzene was carried out in the presence of palladium acetate and acetic acid. It was concluded that, although the usual olefins predominantly undergo phenylation, an olefin which can easily form a π-allyl complex gives acetates as major products under the present reaction conditions.

Aromatic substitution of olefin—IX : Reactions of olefins containing a polar group with benzene

Abstract The phenylation of olefins containing a polar group was carried out in the presence of palladium acetate and acetic acid. The reaction mechanism is discussed.

Stable palladium(II) carbonyl complexes containing palladium-carbon σ-bonds

Abstract Halo(2- N - dihapto -aromatic oxime)palladium(II) carbonyl compounds containing palladium-carbon σ-bonds have been synthesized by bridge-splitting reactions of di-μ-halobis(2, N - dihapto -aromatic oxime)dipalladium(II) (halogen (halogen z.dbnd; Cl, Br, or I) with carbon monoxide. These compounds are very stable in a dry atmosphere, and their structures, which include strong intramolecular hydrogen bonds, are discussed in terms of their IR spectra. The CO and OH stretching frequencis show a marked dependence on the nature of the halogen; v (CO), Cl- ⪢ Br- ⪢ I-complex and v (OH), I- ⪢ Br- ⪢ Cl-complex. These variations are predominantly due to inductive effects.

Aromatic substitution of olefin—VIII : Substituent effects on the reactions of styrene with monosubstituted benzenes in the presence of palladium(II) salts

Abstract In the reactions of styrene with monosubstituted benzenes such as toluene, ethylbenzene, anisole or chlorobenzene in the presence of palladium(II) salts, the direction of substitution but not the reactivity is strongly influenced by the substituent on a benzene ring.