Chemistry

Boric acid (BO3H3) is an inexpensive, efficient and mild catalyst for the synthesis of 2,4,5-triaryl-1H-imidazoles in excellent yields from the one-pot three-component condensation of benzil/benzoin, an aldehydes and ammonium acetate in aqueous media under ultrasound at room temperature. The remarkable advantages offered by this method are green catalyst, mild reaction conditions, simple procedures, much faster reactions and excellent yield of products.

A simple, highly efficient and environmentally benign method for the efficient conversion of 2hydroxyalkyl/aryl ketoximes to 1,2-benzisoxazoles in the presence of catalytic amount of basic ionic liquid 1butyl-3-methylimidazolium hydroxide ([bmim]OH) carried out under the influence of microwave irradiation. This method gives remarkable advantages such as short reaction times (30-60 sec), simple work-up procedure and excellent yields (85-96%). The ionic liquid was successfully reused for four cycles without significant loss of activity.

Alum (KAl(SO4)2․12H2O) is an inexpensive, efficient, non-toxic and mild catalyst for the synthesis of bis(indolyl)methanes by the reaction of 1H-indole with various aldehydes/ketones under the influence of ultrasound irradiation in solvent-free condition. The remarkable advantages of this method are the simple experimental procedures, shorter reaction times, high yields of product and green aspects by avoiding toxic catalysts and solvents.

In this present study, some new 1-thiazolyl-2-pyrazoline derivatives were prepared by the base catalyzed condensation of 4-(2'-hydroxy-5'-chlorophenyl)-2-hydrazino-thiazole and pyrazole containing chalcones in polyethylene glycol (PEG-400) as a green reaction medium.

Efficient Synthesis of Benzimidazo[1,2-a]pyrimidinone Derivatives via Catalyst--Free Reactions of Baylis-Hillman Acetates, Alcohols, and Amines with 2-Aminobenzimidazole. -The title compounds, e.g. (III) and (V), are prepared by an efficient and facile one-pot process without the use of any catalyst or additive. -(WANG, Y.; SHAFIQ, Z.; LIU*, L.; WANG, D.; CHEN, Y.-J.; J.

An Efficient Synthesis of 2,4,5-Triaryl-1H-imidazole Derivatives Catalyzed by Boric Acid in Aqueous Media under Ultrasound-Irradiation. -Advantages of the title method are the green catalyst, mild reaction conditions, fast reaction and excellent yields. -(SHELKE, K. F.; SAPKAL, S. B.; SONAR, S. S.; MADJE, B. R.; SHINGATE, B. B.; SHINGARE*, M. S.; Bull. Korean Chem.

A simple, highly efficient and environmentally benign method for the synthesis of 3-styrylchromones from 3-formylchromones and 4-nitrophenylacetic acid/4-nitrotolune in the presence of catalytic amount of basic ionic liquid 1-butyl-3-methylimidazolium hydroxide [(bmim)OH] carried out under the influence of microwave irradiation. This method gives remarkable advantages such as, short reaction times, simple work-up procedure and moderate to good yields. The ionic liquid was successfully reused for four cycles without significant loss of activity.

α-aminophosphonates could be obtained in excellent yields via the solvent-free three component coupling of aldehydes, amines and triethyl phosphite using ammonium metavanadate (H 4 NO 3 V) as a catalyst in one pot procedure at room temperature

An efficient and easy method for one-pot three-component synthesis of amidoalkyl naphthols by the condensation of aromatic/heteroaromatic/aliphatic aldehydes, 2-naphthol and amides or urea under thermal condition at 60 o C in the presence of acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulphate ([bmim]HSO4) has been described.

2,4,5-Triarylimidazoles could be obtained in excellent yields by the one-pot three-component condensation of benzil/benzoin, aldehydes and ammonium acetate in the presence of catalytic amount of the inexpensive, readily available and non-toxic ceric (IV) ammonium nitrate (CAN) in aqueous media under ultrasound at room temperature. In this reaction the products were obtained in short reaction time and easy operation under mild conditions.

Ionic liquid catalyzed one-pot synthesis of hexahydroquinoline derivatives using substituted aryl aldehydes, dimedone, malononitrile and ammonium acetate has been described under microwave irradiation. The protocol has been utilized mild reaction conditions, excellent yield, shorter reaction time and simple workup procedure. The synthesized derivatives were obtained in 80-95% yields and were characterized by IR, 1 H NMR, and mass spectra.

Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity. Key Words: Nickel, Nanoparticles, Biginelli reaction, Aldehydes, UV-visible