Ca(NO3)2•4H2O-catalysed Biginelli Reaction: One-pot Synthesis of 1,2,3,4-Tetrahydropyrimidin-2-ones/pyrimidine-2-thiones under Solvent-free Conditions

The synthesis of 1,2,3,4-dihydropyrimidinone/thione derivatives was achieved in good to excellent yields using calcium(II) nitrate as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, β-keto compounds and urea or thiourea. The reaction was carried out under solvent-free conditions.     

Sidelobe Level Reduction in Linear Array Pattern Synthesis Using Particle Swarm Optimization

The design of nonuniformly spaced linear array antennas using Particle Swarm Optimization method is considered. The purpose is to match a desired radiation pattern and improve the performance of these arrays in terms of sidelobe level. This performance criterion determines how well the system is suitable for wireless communication applications and interference reduction. Two approaches are considered: in the first, the design of element placement with the constraint of array length being imposed is performed. The second is based on element position perturbation starting from a uniform element distribution. Many examples are treated to show the effectiveness of the designs and the effect some other parameters might have on the overall performance of the array.     

Rapid access to novel 2-alkylthiopyrimidine derivatives and attempt of their Tacrine analogs synthesis

A variety of novel 2-alkylthiopyrimidines were synthesized through simple condensation of arylidenemalononitriles with different 2-alkylthiouronium halide derivatives catalyzed by anhydrous potassium carbonate (K₂CO₃). The reactions have been carried out under mild conditions in i-PrOH, and the products were obtained in moderate to good yields with a simple work-up method. Subsequently, some examples of these compounds have been converted into Tacrine analogs by applying the Friedländer reaction.     

AlCl3-promoted reaction of cycloalkanones with hydrazones: a convenient direct synthesis of 4,5,6,7-tetrahydro-1H-indazoles and their analogues

The AlCl₃-promoted reactions of cycloalkanones with hydrazones are described. This approach represents a mild and operationally simple method to access 2,3-diaryl-4,5,6,7-tetrahydro-1H-indazoles and their analogues in good to moderate yields.     

A one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones catalyzed by triphenylphosphine as Lewis base

We report herein the use of triphenylphosphine (TPP) as a new catalyst for the one-pot Biginelli reaction coupling of β-ketoesters, aldehydes and urea (or thiourea) to afford the corresponding dihydropyrimidinones/thiones.     

Synthesis of Some New 1,4‐Dihydropyridine Derivatives through a Facile One‐pot Hantzsch Condensation Catalyzed by Triethylamine

A facile and efficient synthesis of new 1,4‐dihydropyridine derivatives was reported via Hantzsch three‐component condensation reaction of aldehydes or formylphenylboronic acids, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of triethylamine under solvent‐free conditions. The method described here offers several advantages including high yields, short reaction times, and simple work‐up procedure.     

Cd(NO3)2.4H2O Catalyzed One‐Pot Synthesis of 1,4‐Dihydropyridine and Polyhydroquinoline Derivatives through the Hantzsch Multicomponent Condensation

The synthesis of various 1,4‐dihydropyridine and polyhydroquinoline derivatives was achieved in good to excellent yields using cadmium (II) nitrate as catalyst to promote the classical and modified Hantzsch conditions in good yields under mild conditions.     

Phenylboronic acid as an efficient and convenient catalyst for a three-component synthesis of tetrahydrobenzo[b]pyrans

Phenylboronic acid, a non-toxic compound, is used as catalyst for an efficient, rapid, and one-pot three-component synthesis of tetrahydrobenzo[b]pyrans in good to excellent yields. This new procedure has the advantages of operational simplicity, shorter reaction time, higher yields and minimum pollution of the environment.     

Phenylboronic acid as a mild and efficient catalyst for Biginelli reaction

The synthesis of 3,4-dihydropyrimidinone derivatives was achieved in good to excellent yields using phenylboronic acid as catalyst to promote the Biginelli three-component condensation of a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea.