Aerobic oxidative homocoupling reaction of anilides using heterogeneous metal catalysts

We have developed a heterogeneous catalytic oxidative homocoupling reaction of dimethoxyanilides under an oxygen atmosphere. The resulting homo-dimers are useful for the construction of heterocycles, demonstrating the potential of heterogeneous metal catalysts.     

Generation of all carbon quaternary stereocenters at the C-3 carbon of piperidinones and pyrrolidinones and its application in natural product total synthesis

Methodologies regarding the construction of an all carbon quaternary stereocenters at C-3 of lactams have posed significant challenges in the total synthesis of natural products. This review summarizes the advancements for the construction of an all carbon quaternary stereocenters at C-3 of piperidinones and pyrrolidinones and its application in the total synthesis of biologically active and architecturally complex alkaloids.     

Homocoupling of aryl halides promoted by an NiCl2/bpy/Mg system in DMF

Homocoupling of aryl halides (2 ArX → Ar―Ar) promoted by NiCl₂/2,2′‐bipyridine (bpy)/Mg mixtures in DMF has been studied. Mixtures of NiCl₂, bpy and Mg in DMF promoted homocoupling of aryl halides such as phenyl bromide and p‐tolyl bromide to give the coupling products in good (e.g. approximately 60–75%) yields, and the homocoupling products were easily isolated from the reaction mixtures. Application of this homocoupling to dibromo‐aromatic compounds (Br–arylene–Br: 2,5‐dibromopyridine, 2,7‐dibromo‐9.9‐dioctylfluorene and 2,7‐dibromo‐9,10‐dioctyl‐9,10‐dihydrophenanthrene) gave the corresponding π‐conjugated polymers, –(arylene)_n–, in good yields. Organometallic processes for the homocoupling are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Iron-catalyzed decarboxylative methylation of α,β-unsaturated acids under ligand-free conditions

It is the first time to find that iron-catalyzed decarboxylative methylation of α,β-unsaturated acids could be performed in the absence of any ligands. During the reaction, the configuration of the double bond could be retained. It is noteworthy that di-tert-butyl peroxide (DTBP) was employed not only as the oxidant, but also as the methyl source.     

Amine‐bridged bis(phenol) ligands for efficient Pd‐catalyzed aqueous C‐C coupling reactions

The influence of ring size ( 5 or 6 ), chain length ( 1 , 2 or 3 ) and bulkiness of N‐aryl substituents in amine‐bridged bis(phenol) ligands ( 1 , 2 , 3 ) on palladium‐catalyzed aqueous C‐C coupling reactions were revealed. The homocoupling of arylboronic acid can be completed in neat water with the aid of a catalytic amount of p‐toluenesulfonyl chloride (TsCl) in a very short time under anaerobic or aerobic conditions. Interestingly, the same catalytic system was efficient for Suzuki–Miyaura reaction in aqueous acetone under aerobic conditions in the absence of TsCl. The crystal structures of ligand 1 and three unsymmetrical fluorine‐substituted biaryl derivatives were also reported. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of 3-acylindoles via decarboxylative cross-coupling reaction of free(N–H) indoles with α-oxocarboxylic acids

A convenient and general method for acylation of free(N–H) indoles via palladium-catalyzed decarboxylative cross-coupling reaction was developed. This process provided a useful method for the preparation of diverse 3-acylindoles in high yields utilizing a reaction with readily accessible reactants under mild conditions.     

Nickel catalyzed decarboxylative alkylation of aryl triflates with anhydrides

Aliphatic acid anhydrides are the versatile building blocks and the new method for the conversion of anhydrides is thus of great significance. Herein, we report the decarboxylative alkylation of aryl triflates with aliphatic acid anhydrides via nickel catalysis. This novel method provides a facile access to construct Csp²-Csp³ bond. In addition, this method is compatible with a broad array of functional groups and exhibits good substrates scope.     

Direct Formation of C−C Triple‐Bonded Structural Motifs by On‐Surface Dehalogenative Homocouplings of Tribromomethyl‐Substituted Arenes

On‐surface synthesis shows significant potential in constructing novel nanostructures/nanomaterials, which has been intensely studied in recent years. The formation of acetylenic scaffolds provides an important route to the fabrication of emerging carbon nanostructures, including carbyne, graphyne, and graphdiyne, which feature chemically vulnerable sp‐hybridized carbon atoms. Herein, we designed and synthesized a tribromomethyl‐substituted compound. By using a combination of high‐resolution scanning tunneling microscopy, non‐contact atomic force microscopy, and density functional theory calculations, we demonstrated that it is feasible to convert these compounds directly into C?C triple‐bonded structural motifs by on‐surface dehalogenative homocoupling reactions. Concurrently, sp³‐hybridized carbon atoms are converted into sp‐hybridized ones, that is, an alkyl group is transformed into an alkynyl moiety. Moreover, we achieved the formation of dimer structures, one‐dimensional molecular wires, and two‐dimensional molecular networks on Au(111) surfaces, which should inspire further studies towards two‐dimensional graphyne structures.     

CuI‐catalyzed homocoupling of terminal alkynes to 1,3‐diynes

A simple and efficient protocol for CuI‐catalyzed oxidative homocoupling reaction of terminal alkynes to symmetrical 1,4‐disubstituted 1,3‐diynes was reported. The reaction can be carried out in the open air, using NaOAc as a base in the absence of any other additives. A variety of terminal alkynes were converted to the corresponding 1.3‐diynes in good to excellent yields without any side product formation. Copyright © 2010 John Wiley & Sons, Ltd.     

Ethanol‐promoted reductive homocoupling reactions of aryl halides catalyzed by palladium on carbon (Pd/C)

Homocoupling reactions of aryl bromides or iodides proceeded smoothly with palladium on carbon (Pd/C) catalyst, ethanol and base in dimethyl sulfoxide (DMSO) to afford exclusively symmetric biaryls in good to excellent yields. Ethanol was first used as a reducing agent in situ to reduce the Pd²⁺/C species into Pd⁰/C active species to complete the catalytic redox cycle. It was found that ethanol can promote the Pd/C‐catalyzed reductive homocoupling of aryl iodides and bromides efficiently in the presence of base. A reaction mechanism has been put forward and discussed. Copyright © 2010 John Wiley & Sons, Ltd.