Palladium-catalyzed direct coupling reaction of propargylic alcohols with arylboronic acids

The direct coupling of propargylic alcohols with arylboronic acids has been achieved using palladium catalyst. Various propargylic alcohols and arylboronic acids can be coupled to afford the corresponding allenic and propargylic arenes, which are selectively produced depending on the substituent on the propargylic alcohol, respectively.     

Regioselective anti-addition of phenols to propargylic oxiranes by palladium(0) catalyst

(Z)-Phenol-substituted alkenes were produced by the palladium(0)-catalyzed reaction of propargylic oxiranes with phenols. The regio- and stereoselective addition of phenols to alkynes occurs via the formation of π-propargyl- and π-allylpalladium complexes. The phenoxy-substituted enones were produced simultaneously depending on the reaction conditions.     

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.     

Nickel(II)-catalyzed addition reaction of arylboronic acids to isatins

A Ni-catalyzed addition of arylboronic acids to isatins was first developed. The reaction, driven by Ni(acac)₂ and dppp as the phosphine ligand, gave 3-aryl-3-hydroxy-2-oxindoles in up to 97% yield. Scopes of benzyl-protected isatins and arylboronic acids were examined. Substituted phenylboronic acids along with fused-ring and heterocyclic boronic acids reacted with isatins smoothly. Preliminary asymmetric catalysis was investigated as well, showing moderate enantioselectivity. The mechanism was also described.     

Palladium-catalyzed carbonylative coupling of benzyl chlorides with aryl boronic acids in aqueous media

A novel chemoselective protocol for the carbonylative Suzuki coupling of benzyl chlorides with aryl boronic acids at low pressure of carbon monoxide has been developed. Applying a commercially available palladium acetate/PCy₃ catalyst system in the presence of potassium phosphate as the base and water as the solvent the coupling reactions proceeded smoothly. To demonstrate the general applicability 12 different α-arylated acetophenones have been synthesized in moderate to good yields (41-78%) under mild conditions.     

Palladium-catalyzed intermolecular coupling of 3-substituted propargylic carbonates with phenols: Synthesis of 2-substituted benzofuran derivatives

We accomplished the synthesis of 2-substituted benzofuran derivatives by the palladium-catalyzed reaction of 3-substituted propargylic carbonates with phenols. The 2-substituted benzofuran derivatives were obtained through the intermolecular coupling of the 3-substituted propargylic carbonates with phenols, and sequential intramolecular cyclization reaction.     

Palladium-catalyzed diastereoselective coupling of propargylic oxiranes with terminal alkynes

[reaction: see text] A diastereoselective coupling of propargylic oxiranes with terminal alkynes has been developed with use of a palladium catalyst. The stereochemistries of the resulting 4-alkynyl-substituted 2,3-allenols have been altered depending on the palladium catalyst. An optically active anti-substituted allene was synthesized from the reaction of an enantiomerically enriched propargylic oxirane without loss of chirality.     

Palladium-bipyridine catalyzed conjugate addition of arylboronic acids to α,β-unsaturated carbonyl compounds in aqueous media

Palladium/bipyridine catalyzed conjugate addition of arylboronic acids to α,β-unsaturated carbonyl compounds in aqueous media was developed with high yields.     

Thiosemicarbazone salicylaldiminato palladium(II)-catalyzed alkynylation couplings between arylboronic acids and alkynes or alkynyl carboxylic acids

An efficient catalytic system has been developed for the synthesis of unsymmetrical substituted alkynes via the thiosemicarbazone salicylaldiminato palladium(II)-catalyzed alkynylation couplings between arylboronic acids and alkynes or alkynyl carboxylic acids under mild conditions.     

Palladium-catalyzed hydroarylation of alkynes with arylboronic acids

Reaction of symmetrical and unsymmetrical alkynes with arylboronic acids, using PdCl₂ as catalyst source and i-Pr₂NPPh₂ as ligand, afforded trisubstituted alkenes with regioselectivity in good to excellent yields without a common additional acetic acid. Its efficiency has been demonstrated by its good functional groups, high yield and crowded substrates.     

Palladium-catalyzed coupling of pyrazole triflates with arylboronic acids

[reaction: see text] A general protocol for the palladium-mediated Suzuki coupling reaction of pyrazole triflates and aryl boronic acids has been developed. The use of additional dppf ligand was determined to increase product yields allowing for the use of a broad range of reaction substrates.     

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.     

Efficient coupling of heteroaryl halides with arylboronic acids in the presence of a palladium-tetraphosphine catalyst

Cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane:·1/2[PdCl(C₃H₅)]₂ system catalyses the Suzuki cross-coupling of heteroaryl halides with a range of arylboronic acids with very high ratio substrate/catalyst in good yields. Substrates such as pyridines, quinolines, thiophenes, an indole, pyrimidines or a furane have been used successfully.     

Palladium‐Catalyzed Coupling of Propargylic Alcohols with Boronic Acids under Ambient Conditions

A highly efficient palladium‐catalyzed direct coupling of propargylic alcohols with organoboronic acids to synthesize tri‐ and tetra‐substituted allenes has been developed under mild reaction conditions. Many useful functional groups are tolerated in this process with high to excellent yields. Preliminary biological studies showed that several tri‐ and tetra‐substituted allenes exhibited potent anti‐diabetic activities.     

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.     

Synthesis of 2-arylindoles by Suzuki coupling reaction of 3-bromoindoles with hindered benzoboronic acids

A new synthetic method for 2-arylindoles has been developed, the process through Suzuki coupling reaction of 3-bromoindoles with hindered boronic acid catalyzed by Pd(OAc)₂/PCy₃, and a series of 2-arylindoles have been synthesized in moderate to high yields.     

Palladium-catalyzed coupling reaction of amino acids (esters) with aryl bromides and chlorides

The bulky and electron-rich MOP type ligands and Pd(dba)₂ combinations showed high efficiency for the coupling reactions of amino acids and inactive aryl halides to give N-aryl amino acids. Under the catalytic conditions, not only α-amino acids, but also β-, γ-, and δ-amino acids have been coupled with aryl chlorides in moderate to high yields; in the case of optically pure β-amino acids as substrates, the optical purities of the coupling products retained.     

Synthesis of ene-allenes via palladium-catalyzed hydride-transfer reaction of propargylic amines under mild conditions

The palladium-catalyzed allene transformation reaction from propargylic amines proceeded in the presence of Pd₂(dba)₃·CHCl₃ (5 mol %) and (C₆F₅)₂PC₂H₄P(C₆F₅)₂ (10 mol %) in CHCl₃ at room temperature to give the corresponding allenes in good to high yields. Dicyclohexyl groups substituted on the nitrogen of propargylic amines were found to be effective for the current transformation and the conjugated ene-allenes 4 were synthesized from the corresponding propargylic amines 3 under mild conditions.     

Palladium mediated direct coupling of silylated arylalkynes with propargylic chlorides: an efficient access to functionalized conjugated allenynes

Pd/Cu-catalyzed one-pot reaction of 1-trimethylsilyl-2-arylalkynes with propargylic chlorides in the presence of TBAF is described. The present new procedure is applicable to a wide range of silylated arylalkynes with both electron-withdrawing and electron-donating substituents. Functionalized allenynes can thus be obtained in good yields without prior deprotection of the alkynes.