Preparation of Unsymmetrical Biaryls by Pd(II)-Catalyzed Cross-Coupling of Aryl Iodides

The Ullmann homo- and cross-couplings of aryl iodides are carried out to afford symmetrical and unsymmetrical biaryls in moderate to good yields in a catalytic system of Pd(OAc)2/K2CO3/MeCOEt. The high selectivity of unsymmetrical biaryl products in cross-couplings mainly depends on the reactivity difference between two iodoarene substrates and their employed ratios

Palladium-Catalyzed β‑Arylation of Amide via Primary sp³C–H Activation

A β-arylation of primary sp³C–H bonds on simple amides such as pivalamides with aryl iodides/CF₃CO₂Ag has been established successfully at 120 °C in a Pd­(OAc)₂ (catalyst)/CF₃CH₂OH (solvent) system. Pivalamides including ^<i>t</i>BuCONH₂, ^<i>t</i>BuCONHR, and ^<i>t</i>BuCONR₂ undergo the arylations smoothly to afford β-aryl pivalamides in moderate to good yields. Various aryl iodides are available bearing either electron-donating or electron-withdrawing substituted groups in the coupling reactions

Phosphine-Free Palladium(II)-Catalyzed Arylation of Naphthalene and Benzene with Aryl Iodides

A phosphine-free arylation of naphthalene and benzene with aryl iodides to give biaryls in moderate to good yields is carried out in the presence of catalytic Pd(OAc)2 and stoichiometric CF3CO2 Ag in TFE or/and TFA

Palladium-Catalyzed β‑Acyloxylation of Simple Amide <i>via</i> sp³ C–H Activation

β-Acyloxy amides are prepared in moderate to high yields by palladium-catalyzed acyloxylation of primary sp3 C–H bonds from simple amides without any special directing group. A catalytic system of Pd­(OAc)2/CF3CO2H/K2S2O8 is available to various amides with N-substituted by linear alkanes, cyclic alkanes, and electron-deficient benzyl compounds in this reaction. Acyloxylated products could be transformed easily to the corresponding β-hydroxy amides

Palladium(II)-Catalyzed Oxidative Homo- and Cross-Coupling of Aryl <i>ortho</i>-sp² C–H Bonds of Anilides at Room Temperature

The preparation of secondary 2,2′-bisanilides has been successfully achieved through an oxidative coupling of aryl <i>ortho</i>-sp² C–H bonds of anilides in the presence of catalytic Pd­(OAc)₂ and K₂S₂O₈ as an oxidant in MsOH/CF₃CO₂H (TFA) at room temperature (25 °C). The aromatic rings of anilides substituted by various electron-donating or electron-withdrawing groups are tolerant in these coupling reactions

Palladium(II)-Catalyzed Coupling of Electron-Deficient Arenes via C–H Activation

Homocoupling and cross-coupling of electron-deficient arenes, including nitrobenzene, (trifluoromethyl)­benzene, ethyl benzoate, etc., have been developed to afford biaryls using a catalytic system of Pd­(OAc)₂/trifluoroacetic acid (TFA)/O₂ or K₂S₂O₈. The crucial step is to tune the concentrations of arenes and the loading of TFA carefully to enhance the reaction rates and the selectivity of these couplings involving dual C–H activation

Palladium(II)-Catalyzed Coupling of <i>p</i>-Xylene via Regioselective C−H Activation in TFA

A homocoupling of p-xylene to afford biaryl- or diarylmethane as a major product has been carried out in a catalytic system of Pd(OAc)2/CF3CO2H (TFA)/K2S2O8. In this coupling reaction, the aryl and benzylic C−H bonds of p-xylene can be selectively activated just by tuning the concentration of TFA

Intermolecular Cross-Coupling of Simple Arenes via C−H Activation by Tuning Concentrations of Arenes and TFA

Formation of unsymmetrical biaryls from simple arenes has been achieved successfully in a catalytic system of Pd(OAc)2/CF3CO2H(TFA)/K2S2O8 just by tuning the concentrations of arenes and TFA under mild conditions. A proposed mechanism containing two-step aromatic C−H activation on this novel intermolecular cross-coupling of arenes is also suggested and partly supported by experiments

One-Pot Preparation of Arylalkynes by a Tandem Catalytic Iodination of Arenes and Palladium-Catalyzed Coupling of Iodoarenes with Terminal Alkynes

Iodination of activated arenes by air-oxidation is carried out in the presence of catalytic bismuth salts at room temperature. Subsequently, the formed iodoarenes react with terminal alkynes to give arylalkynes under a selected palladium-catalyzed coupling condition in the same pot