An efficient Stille cross-coupling reaction catalyzed by Pd(OAc)2/DAB-Cy catalytic system

An efficient palladium-catalyzed Stille cross-coupling reaction has been developed. In the presence of 3 mol% of Pd(dba)₂ and 6 mol% of DAB-Cy (1,4-dicyclohexyl-diazabutadiene), various aryl halides (iodides and bromides) were coupled with organotin compounds to afford the corresponding biaryls and alkyne in good to excellent yields. Furthermore, high TONs [turnover numbers, TONs up to 950,000 for the reaction of 1-iodo-4-nitrobenzene and tributyl(phenyl)stannane] for the Stille cross-coupling reaction were observed.     

Oxidative cross-coupling of acrylates with vinyl carboxylates catalyzed by a Pd(OAc)2/HPMoV/O2 system

Oxidative cross-coupling of acrylates with vinyl carboxylates was first successfully achieved by the use of a Pd(OAc)(2)/HPMoV/O(2) system in fair to good yields. For instance, the reaction of n-butyl acrylate with vinyl acetate in the presence of catalytic amounts of Pd(OAc)(2) and H(4)PMo(11)VO(40).nH(2)O under O(2) in acetic acid at 70 degrees C for 12 h afforded the corresponding cross-coupling product, n-butyl 5-(acetoxy)-2,4-pentadienoate, in 70% yield.     

Cu（OAc）2 catalyzed Sonogashira cross-coupling reaction in amines

A simple Cu(OAc)_2 catalyzed Sonogashira coupling protocol is presented.It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields,using Cu(OAc)_2 as the catalyst and Et3N as the solvent.     

Recyclable and reusable Pd(OAc)2/DABCO/PEG-400 system for Suzuki-Miyaura cross-coupling reaction

[reaction: see text] A stable and efficient Pd(OAc)2/DABCO (triethylenediamine) catalytic system for Suzuki-Miyaura cross-coupling reaction has been developed. In the presence of Pd(OAc)2 and DABCO, coupling of aryl halides with arylboronic acids was carried out smoothly to afford good to excellent yields and high turnover numbers (TONs) (the maximal TONs were up to 960,000 for the reaction of 1-iodo-4-nitrobenzene with phenylboronic acid) using PEG-400 as the solvent. Moreover, the Pd(OAc)2/DABCO/PEG-400 system could be recycled and reused five times without any loss of catalytic activity for aryl iodides and bromides.     

Pd(OAc)2/DABCO-catalyzed Suzuki-Miyaura cross-coupling reaction in DMF

The scope and limitations of the Pd(OAc)₂/DABCO (1,4-diaza-bicyclo[2.2.2]octane)-catalyzed Suzuki-Miyaura cross-coupling reactions have been demonstrated. The results showed that the effect of solvent had a fundamental influence on the reaction. In the presence of Pd(OAc)₂ and DABCO, both aryl bromides and aryl chlorides all worked well with arylboronic acids to form biaryls, heteroaryl-aryls, and biheteroaryls in moderate to excellent yields using DMF as the solvent. Additionally, the reactions of aryl bromides were conducted under relatively mild conditions.     

Suzuki-Miyaura cross-coupling reaction catalyzed by Pd/MgLa mixed oxide

A new, reusable Pd/MgLa mixed oxide catalyst has been applied successfully in the Suzuki-Miyaura carbon-carbon cross-coupling reaction of aryl halides as well as benzylic bromide with boronic acids in ethanol. The catalyst is air stable, can be stored and handled under an ambient atmosphere and after the reaction it can be recovered by simple filtration and reused without significant loss of activity.     

Efficient double bond migration of allylbenzenes catalyzed by Pd(OAc)2-HFIP system with unique substituent effect

A novel catalyst system of Pd(OAc)₂-HFIP induces double-bond migration of allylbenzenes under mild conditions with low catalytic loading to afford 1-propenylbenzenes. The reaction shows a unique substituent effect that is highly dependent on the distance of substituents from the allylic moiety. Thus, the reactivity of substrates bearing a methyl group is ordered in para > meta > ortho, whereas it is entirely reversed as ortho > meta > para for methoxy and chloro substituents.     

Efficient homo-coupling reactions of heterocyclic aromatic bromides catalyzed by Pd(OAc)2 using indium

Homo-coupling reactions of heterocyclic aromatic bromides smoothly proceeded with cat-Pd(OAc)₂, indium, and LiCl in DMF to afford exclusively symmetric biaryls possessing heterocyclic aromatic ring in good to excellent yields.     

Guanidine/Pd(OAc)2-catalyzed room temperature Suzuki cross-coupling reaction in aqueous media under aerobic conditions

A highly efficient Pd(OAc)2/guanidine aqueous system for the room temperature Suzuki cross-coupling reaction has been developed. The new water-soluble and air-stable catalyst Pd(OAc)2.(1f)2 from Pd(OAc)2 and 1,1,3,3-tetramethyl-2-n-butylguanidine (1f) was synthesized and characterized by X-ray crystallography. In the presence of Pd(OAc)2.(1f)2, coupling of arylboronic acids with a wide range of aryl halides, including aryl iodides, aryl bromides, even activated aryl chlorides, was carried out smoothly in aqueous solvent to afford the cross-coupling products in good to excellent yields and high turnover numbers (TONs) (TONs up to 850,000 for the reaction of 1-iodo-4-nitrobenzene and phenylboronic acid). Furthermore, this mild protocol could tolerate a broad range of functional groups.     

Efficient C–H activation of alkylbenzenes and methylcyclohexenes to benzyl esters by Pd(OAc)2/Sn(OAc)2 catalyst system

Selective activation of the side-chain C–H bond of alkylbenzenes and methylcyclohexenes is achieved by a Pd(OAc)₂/Sn(OAc)₂ catalyst system. Under an oxygen atmosphere, various benzyl esters were obtained from the substrates and carboxylic anhydrides. The esters were obtained in more than 100% yield based on the amount of benzoic anhydride, and consumption of oxygen was observed. This suggests that oxygen may be incorporated to produce two moles of the benzoxyl group from one mole of benzoic anhydride. It is interesting that either 1-, 3- or 4-methylcyclohexene reacted with benzoic anhydride to give benzyl benzoate. These carboxylations proceeded at the side-chain alkyl group with high selectivity and no ring-carboxylated product or coupling product was detected. From these results, a mechanism involving the formation of a η³-benzylpalladium complex was proposed. © 1997 John Wiley & Sons, Ltd.     

Pd2(dba)3/P(i-BuNCH2CH2)3N-catalyzed Stille cross-coupling of aryl chlorides

[reaction: see text] The Pd(2)(dba)(3)/P(i-BuNCH(2)CH(2))(3)N (1d) catalyst system is highly effective for the Stille cross-coupling of aryl chlorides with organotin compounds. This method represents only the second general method for the coupling of aryl chlorides. Other proazaphosphatranes possessing benzyl substituents also generate very active catalysts for Stille reactions. Noteworthy features of the method are: (a) commercial availability of ligand 1d, (b) the wide array of aryl chlorides that can be coupled, and (c) applicability to aryl, vinyl, and allyl tin reagents.     

Ligand-free Stille cross-coupling reaction using Pd/CaCO3 as catalyst reservoir

Stille reactions between halobenzenes and other substituted (hetero)arenes and tributylphenyltin were carried out in ethanol-water solution using Pd/CaCO₃ as catalyst in a ligand-free system. The catalyst could be recycled three times without any loss of activity. The ethanol-water solution, after removal of the catalyst and extraction of the product, was found to have catalytic activity, thus showing the presence of soluble Pd(0)/Pd(II) species that can be regarded as the true catalysts.     

丙酮为溶剂Pd(OAc)2催化的Heck反应研究

研究了无需外加配体、在丙酮溶剂中Pd(OAc)2催化的Heck反应.得到的反应最优结果是:Pd( OAc)2(1 mol%)为催化剂,K2CO3(1.2 equiv.)为添加剂,以廉价易得的丙酮为溶剂,在100℃下各种碘代芳烃(1equiv.)可以顺利地与丙烯酸乙酯、苯乙烯和乙烯环已烷等烯基化合物(2 equiv.)发...     

CuI/Dabco as a highly active catalytic system for the Heck-type reaction

An efficient catalytic system using CuI/Dabco (triethylenediamine) for the Heck-type cross-coupling reaction was developed. In the presence of 10 mol % of CuI and 20 mol % of Dabco, the coupling of various aromatic iodides and 1-((Z)-2-bromovinyl)benzene with olefins was carried out efficiently and selectively to afford the corresponding internal olefins in moderate to good yields.     

Efficient Stille cross-coupling reaction using aryl chlorides or bromides in water

An efficient Stille cross-coupling reaction using a variety of aryl halides in neat water has been developed. Employing palladium-phosphinous acid catalyst [(t-Bu)(2)P(OH)](2)PdCl(2) allows formation of biaryls from aryl chlorides and bromides in good to high yields. Functional groups such as ketones and nitriles are tolerated, and organic cosolvents are not required. The air stability and solubility in water of the palladium complexes used in this study facilitate operation of the coupling reaction and product isolation. The feasibility of catalyst recycling has also been demonstrated.     

Pd(OAc)_2/HQ/FePc、Pd(OAc)_2/FePc 催化烯烃氧化合成酮的研究

考察了在乙腈酸性水溶液中Ｐｄ（ＯＡｃ）２／氢醌（ＨＱ）／酞青铁（ＦｅＰｃ）和Ｐｄ（ＯＡｃ）２／ＦｅＰｃ对环己烯、环戊烯、苯乙烯、正癸烯氧化合成相应酮的催化活性．实验结果表明，两类催化体系对环戊烯的酮基化均呈现出较高的催化活性，环戊酮收率可达９８％．在其它烯烃的氧化反应中，三元催化体系Ｐｄ（ＯＡｃ）２／ＨＱ／ＦｅＰｃ的催化活性高于二元的Ｐｄ（ＯＡｃ）２／ＦｅＰｃ．这表明，在Ｗａｃｋｅｒ类催化体系中，电子传递体的作用是很重要的．对催化体系中各组分的作用进行了讨论，并给出了可能的催化作用机理．     

PEG-400 promoted Pd(OAc)2/DABCO-catalyzed cross-coupling reactions in aqueous media

PEG-400 [poly(ethylene glycol-400)] was found to improve the Pd(OAc)₂/DABCO-catalyzed aqueous Suzuki-Miyaura and Stille cross-coupling reactions. In the presence of Pd(OAc)₂, DABCO, and PEG-400, a variety of aryl halides were coupled with arylboronic acids or organotin compounds efficiently to afford the corresponding cross-coupled products in moderate to excellent yields. The turnover numbers was up to 900,000 for the Suzuki-Miyaura reaction and up to 9800 for the Stille reaction. The catalyst system was also effective for Heck and Sonogashira cross-coupling reactions to some extent.     

Direct carboxylation reaction of methane with CO by a Yb(OAc)3/Mn(OAc)2/NaClO/H2O catalytic system under very mild conditions

A new method of synthesis of acetic acid in water has been developed from the carboxylation of methane with carbon monoxide using lanthanide catalysts. Ytterbium(III) acetate has been found to be the most active catalyst among the compounds of the lanthanide series in the carboxylation reaction of methane with carbon monoxide. Sodium hypochlorite or hydrogen peroxide was used as the oxidant in this reaction. Sodium hypochlorite exhibited more favorable activity than hydrogen peroxide in the reaction. The catalytic activity was improved by the addition of transition-metal salts such as manganese(II) acetate. The best result has been found at a ratio of manganese(II) acetate to ytterbium(III) acetate of 1:10. The optimum reaction conditions (reaction temperature, 40 °C; time, 20 h; methane, 20 atm; carbon monoxide, 5 atm) have been obtained. © 1998 John Wiley & Sons, Ltd.     

Pd(OAc)(2)-catalyzed oxidative C-H/C-H cross-coupling of electron-deficient polyfluoroarenes with simple arenes

Pd(OAc)(2)-catalyzed intermolecular C-H/C-H cross-coupling reactions between electron-deficient polyfluoroarenes and simple arenes for the synthesis of fluorinated biaryls have been developed. Deuterium-labeling experiments suggested that C-H bond cleavage of the simple arenes rather than the polyfluoroarenes is involved in the rate-limiting step.     

Practical asymmetric Henry reaction catalyzed by a chiral diamine-Cu(OAc)2 complex

The chiral diamine ligand 3 was designed and synthesized from (R,R)-1,2-diphenylethylenediamine, (S)-2,2'-dibromomethyl-1,1'-binaphthalene, and o-xylylene dibromide. The resulting 3-Cu(OAc)2 complex was a highly efficient catalyst for the Henry reaction, giving the various nitroaldols with over 90% ee (up to >99%). The reaction was performed in n-propyl alcohol at room temperature, and the Henry adducts were produced in high yield with excellent enantiomeric excess; these attributes are desirable in a catalyst for practical use.