Zhanguo Chen

A Facile and Practical Copper Powder-Catalyzed, Organic Solvent- and Ligand-Free Ullmann Amination of Aryl Halides

A facile and practical method that the copper powder-catalyzed Ullmann amination of aryl halides with aqueous methylamine under organic solvent- and ligand-free condition at 100 °C and in air gave N-arylamines as sole products in good to excellent yields. The presence of a small amount of air is essential. Other aliphatic primary amines show good to very high reactivity. Secondary amines and aniline are not reactive. Sensitive substituents (i.e., CHO, MeCO, CN and Cl) are tolerable in the reaction.

PdEDTA Held in an Ionic Liquid Brush as a Highly Efficient and Reusable Catalyst for Suzuki Reactions in Water

An efficient and reusable catalyst with PdEDTA immobilized in an ionic liquid brush and a green procedure have been developed for coupling aryl iodides and bromides with phenylboronic acid. These reactions were conducted in water under aerobic conditions with water-insoluble or even solid aryl halides. The protocol has the advantages of excellent yields, environmental friendliness, and catalyst recyclability. There was no apparent loss of catalyst efficiency until the 10th cycle.

Copper powder-catalyzed regio- and stereoselective aminobromination of alpha,beta-unsaturated ketones with TsNH2 and NBS as nitrogen and halogen sources.

The regio- and stereoselective aminobromination of alpha,beta-unsaturated ketones catalyzed by copper powder has been established with 4-TsNH(2) and NBS as the nitrogen/bromine sources, respectively. This method provides an easy access for preparation of vicinal aminohalo derivatives in the presence of 1 mol % catalyst. Electron-rich alpha,beta-unsaturated ketones afforded the corresponding aminobrominated products in excellent yields (up to 99.8%), revealing that the addition has an electrophilic feature.

Silicon powder: the first nonmetal elemental catalyst for aminobromination of olefins with TsNH(2) and NBS.

Silicon powder was found, for the first time, to be an efficient alternative to transition metal catalysts for aminobromination of alpha,beta-unsaturated carbonyl compounds and simple olefins with p-toluenesulfonamide (4-TsNH(2)) and NBS, affording the aminobrominated products in high yields and regio- and stereoselectivity. The high reactivity of electron-rich substrates reveals that the reaction has the electrophilic addition feature.

K3PO4-Catalyzed Regiospecific Aminobromination of β-Nitrostyrene Derivatives with N-Bromoacetamide as Aminobrominating Agent

A very simple, efficient, and regiospecific protocol for aminobromination of a wide scope of beta-nitrostyrene derivatives with N-bromoacetamide (NBA) as nitrogen/bromine sources has been developed by using K(3)PO(4) as catalyst. The reaction proceeded smoothly and cleanly to give the bromoamines in good to excellent yields (78-99%) within 24 h in CH(2)Cl(2) at room temperature without protection of inert gases. A possible mechanism involving a nucleophilic conjugate addition was proposed.

Synthesis of 2-oxazolines from ethyl α-cyanocinnamate derivatives with acetamide and N-bromosuccinimide

An efficient method for the one-pot synthesis of 2-oxazolines from ethyl α-cyanocinnamate derivatives with acetamide and N-bromosuccinimide(NBS) in the presence of K3PO4 was developed. The reaction was performed smoothly and cleanly to give 2-oxazolines in good to excellent yields(up to 95%) in acetone at room temperature. Thirteen examples were investigated and the results indicated that a large range of α-cyanocinnamate derivatives could be suitable for this method. Based on the outcomes of experiment, a possible consecutive nucleophilic addition-cyclization pathway was proposed.

K 3 PO 4 -Catalyzed Regiospecific Bromoamidation of β , β -Dicyanostyrene Derivatives with N -Bromoacetamide(NBA)

An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide (NBA) was developed. This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines in excellent yields(up to 99%) at room temperature in the presence of anhydrous K3PO4 as a catalyst without the protection of the inert gaseous in CH2Cl2. A total of 11 examples were investigated and all the products showed the regionspecific feature. Based on the observation of different activities for the different substrates involving the electron-rich or electron-deficient β,β-dicyanostyrenes, a possible Michael addition mechanism was proposed.

A novel class of C3d symmetrical molecules synthesized by a six-fold substitution from 1,4,5,8,9,12-hexabromododecahydrotriphenylene

The synthesis of a novel class of hexa-arm molecules with C(3d) symmetry via a simultaneous six-fold nucleophilic substitution reaction from 1,4,5,8,9,12-hexabromododecahydrotriphenylene has been described.

Aminobromination of ethyl α -cyanocinnamate derivatives with 1,3-dibromo-5,5-dimethylhydantoin(DBDMH) as nitrogen and halogen sources

Abstract1,3-Dibromo-5,5-dimethylhydantoin(DBDMH) was found to be a new and efficient nitrogen/halogen source for the aminobromination of ethyl α-cyanocinnamate derivatives catalyzed by K3PO4. The reaction afforded the aminobrominated products in high yields at room temperature, and the full regiospecificity of all the products were achieved. A possible pathway involving a Michael addition for this aminobromination was suggested.