Phosphine-free cross-coupling reaction of arylboronic acids with carboxylic anhydrides or acyl chlorides in aqueous media

The palladium acetate-catalyzed coupling reaction of aryl boronic acid with carboxylic anhydride or acyl chloride was carried out smoothly in water in the presence of poly(ethylene glycol) (PEG) or 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) to give high yields of ketones without the use of phosphine ligands. The Pd(OAc)2-H2O-[bmim][PF6] catalytic system can be recovered and reused eight times with high efficiency for both carboxylic anhydride and acyl chloride.     

Palladacycle-catalyzed cross-coupling reactions of arylboronic acids with carboxylic anhydrides or acyl chlorides

The triphenylphosphine–cyclopalladated ferrocenylimine (Cat. 2) exhibited highly catalytic activity for the both of arylboronic acids with carboxylic anhydrides and acyl chlorides with low catalyst loading (0.5 mol %). The reactions were unaffected by the presence of electron-releasing and electron-withdrawing substituents in both the arylboronic acids and carboxylic derivatives. Up to 98% yield was obtained for 32 examples. However, they were limited for arylboronic acid with strong electron-withdrawing groups. It is noting that catalyst 2 can be reused for eight times without losing its catalytic activity.     

Triarylantimony dicarboxylates as pseudo-halides for palladium-catalyzed cross-coupling reaction with arylboronic acids and triarylbismuthanes without any base

The reaction of triarylantimony diacetates (6) with organoboron reagents (9) in the presence of Pd(PPh₃)₄ led to the formation of cross-coupling products, biaryls (10, 12 and 14-17), in moderate to excellent yields under mild conditions without any base. Similar reaction of 6 with triarylbismuthanes (18) also gave the corresponding cross-coupling products. Single crystal X-ray analysis of tri(p-tolyl)antimony diacetate (6b) and tris(p-trifluoromethylphenyl)antimony diacetate (6e) revealed the geometry of both central antimony atoms being intermediate between trigonal bipyramidal and pentagonal bipyramidal arrangement with intramolecular coordination between the antimony and two carbonyl oxygen atoms with cis orientation.     

Unprecedented palladium-catalyzed cross-coupling reaction of alpha-bromo sulfoxides with boronic acids

[reaction: see text] A new Suzuki-type palladium-catalyzed reaction of boronic acids with alpha-bromo sulfoxides has been developed using a protocol similar to the well-documented reaction of boronic acids with aryl halides. Both cross-coupling and homocoupling processes were observed. The best yields in cross-coupling products were obtained when the presence of oxygen was carefully excluded using degassed solvents. The oxidative addition palladium complex intermediate could be isolated and characterized by X-ray single-crystal diffraction.     

Suzuki-type cross-coupling reaction of pentavalent triarylantimony diacetates with arylboronic acids without a base

Novel base-free Suzuki-type cross-coupling reaction by the use of triarylantimony diacetates and arylboronic acids in the presence of Pd(PPh₃)₄ catalyst led to the formation of biaryl derivatives in moderate to excellent yields. The reaction is applicable to a variety of arylboronic acids bearing base-sensitive functional groups.     

Palladium-catalyzed cross-coupling reactions of carboxylic anhydrides with organozinc reagents

[reaction: see text] Negishi-type cross-coupling reaction was effected by employing organozincs and anhydrides or mixed anhydrides that formed in situ from sodium salts of the corresponding acids and ethyl chloroformate under the catalysis of palladium(0). A general method for preparing symmetrical/unsymmetrical ketones was developed.     

Boron trifluoride induced palladium-catalyzed cross-coupling reaction of 1-aryltriazenes with areneboronic acids

[reaction: see text] Aryltriazenes are directly coupled with areneboronic acids in the presence of a catalytic amount of Pd(2)(dba)(3) and P(tBu)(3) together with 1 equiv of BF(3).OEt(2) in DME to afford the corresponding biaryl products in up to 98% yield. A carbonylative cross-coupling reaction under a carbon monoxide atmosphere is also found to give the corresponding diaryl ketone with a similar catalyst system.     

Palladium-catalyzed decarboxylative coupling of isatoic anhydrides with arylboronic acids

The decarboxylative coupling of isatoic anhydrides with arylboronic acids was realized for the first time in the presence of Pd(2)(dba)(3) and DPEphos, achieving aryl o-aminobenzoates with yields ranging from moderate to good. The efficiency of this procedure was demonstrated by good compatibility with fluoro, chloro, bromo, nitro, cyano, trifluoromethyl, formacyl, acetyl, thienyl, and naphthyl groups. Preliminary mechanistic experiments using deuterium labeling showed that the oxygen atom was derived from dioxygen.     

Nickel-catalyzed cross-coupling of aryl phosphates with arylboronic acids

The Suzuki-Miyaura cross-coupling of aryl phosphates using Ni(PCy(3))(2)Cl(2) as an inexpensive, bench-stable catalyst is described. Broad substrate scope and high efficiency are demonstrated by the syntheses of more than 40 biaryls and by constructing complex organic molecules. The poor reactivity of aryl phosphates relative to aryl halides is successfully employed to construct polyarenes by selective cross-coupling using Pd and Ni catalysts.     

Suzuki-Miyaura cross-coupling of benzylic phosphates with arylboronic acids

[reaction: see text] Suzuki-Miyaura cross-coupling of benzylic phosphates with arylboronic acids was investigated. Optimum conditions employed the simple catalytic system of palladium(II) acetate (1 mol %) and triphenylphosphine (4 mol %) with either potassium phosphate or potassium carbonate as the base and toluene as the solvent at 90 degrees C. Using the developed conditions, a series of structurally diverse diarylmethanes were prepared.     

Palladium-catalyzed carbonylative cross-coupling reaction of triarylantimony dicarboxylates with arylboronic acids: Synthesis of biaryl ketones

A novel palladium-catalyzed three-component carbonylative coupling reaction by use of triarylantimony diacetate, arylboronic acid and carbon monoxide (1 atm) could be attained under mild reaction conditions without any base as an additive. The reaction can be applied to a wide range of triarylantimony diacetates and boronic acids to afford the corresponding unsymmetrical biaryl ketones in good yields.     

Suzuki-Miyaura cross-coupling of benzylic carbonates with arylboronic acids

The cross-coupling of benzylic carbonates with arylboronic acids gave the corresponding diarylmethanes in high yields by use of the palladium catalyst generated in situ from [Pd(eta(3)-C(3)H(5))Cl](2) and 1,5-bis(diphenylphosphino)pentane (DPPPent). The Suzuki-Miyaura reaction using DPPPent-palladium catalyst is applicable to syntheses of a broad range of functionalized diarylmethanes. [reaction: see text]     

Suzuki cross-coupling of solid-supported chloropyrimidines with arylboronic acids

The utility of the Suzuki cross-coupling to synthesize biaryl compounds is expanded herein to include reactions of resin-supported chloropyrimidines with boronic acids. In particular, an efficient method is described for the synthesis of a library of biaryl compounds from solid-supported chloropyrimidines. The Suzuki reaction was performed in an inert atmosphere using Pd(2)(dba)(3)/P(t-Bu)(3) as catalyst, spray-dried KF as base, and THF as solvent. The reaction was allowed to proceed overnight at 50 degrees C. Upon cleavage with acid, a library of 4-(substituted amino)-6-arylpyrimidines was obtained in moderate yield and high purity.     

Mechanism of the palladium-catalyzed addition of arylboronic acids to enones: a computational study

The palladium(II)-catalyzed addition of arylboronic acids to β,β-disubstituted enones has been investigated with the BP86 density functional. The results show that the mechanism requires three steps: transmetalation, alkene insertion, and protonation. The alkene insertion is the rate-determining step. For unactivated alkenes, the Heck-type β-hydride elimination is more favored than protonation.     

Ni-catalyzed cross-coupling reaction of aryl chlorides with arylboronic acids in IPA without using a reducing reagent

The coupling reaction of aryl chlorides with arylboronic acids was successfully performed in isopropanol (IPA) by using [NiCl(Ph₂PCH₂CH₂OH)₂(H₂O)]Cl (5), a cationic Ni(II)-complex, as a precatalyst in the absence of a reducing agent. The coupling reaction proceeded smoothly under mild conditions to provide biaryls in satisfactory to excellent yields, and formation of the undesired dechlorination products of aryl chlorides was completely prevented.     

Base-free Pd-MOF catalyzed the Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborate salts with arylboronic acids

A convenient and environmental benign synthesis of biaryls has been demonstrated by a straightforward reaction catalyzed by the palladium-containing metal-organic framework (Pd-MOF) [Pd (2-pymo)₂]_n (2-pymo = 2-pyrimidinolate). A series of functionalized biaryl derivatives have been synthesized in good to excellent yields by the Suzuki-miyaura cross-couplings of sustainable arenediazonium salts with a variety of arylboronic acids and the reactions were catalyzed by the Pd-MOF using methanol as a benign solvent. Those base- and additive-free catalytic reactions proceeded smoothly under non-anhydrous and non-degassed condition. Such transformation avoided high reaction temperature, tolerated many functional groups and presented a wide substrate scope. The catalyst could be recovered by filtration and reused for four successive cycles before collapse of the MOF structure.     

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones with arylboronic acids

Palladium-catalyzed cross-coupling reactions of 2-diazonaphthoquinones and arylboronic acids proceeded by the treatment with Pd(OAc)₂ in acetic acid to afford 2-aryl-1-naphthols.