Fluoroboric acid supported on silica gel (HBF 4 -SiO 2 ) catalyzes efficiently the three component condensation of an aldehyde, a 1,3-dicarbonyl compound and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones and thiones in high yields. The ambient conditions, fast reaction rates, and excellent product yields are the important characteristics of this reaction.

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Cyanuric chloride is shown to be an extremely efficient catalyst for the synthesis of β-enaminoesters from β-ketoesters under solvent-free conditions by grinding in a mortar with pestle at 25 °C. A short reaction time, an inexpensive and easily available catalyst, mild reaction conditions and excellent yields of the products are attractive features of this methodology.

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Three Component Reaction: An Efficient Synthesis of 3,4-Dihydropyrimidin--2(1H)-ones and Thiones Using Heterogeneous Catalyst. -This procedure offers easy access to dihydropyrimidinones/thiones (IV) and (VII) with a variety of substitution patterns by utilizing a three-component one-pot condensation of dicarbonyl compounds (I) and (V), aldehydes (II) and (VI), and urea/thiourea (III) in the presence of silica-supported fluoroboric acid. Aromatic aldehydes provide the corresponding dihydropyrimidinones in good to excellent yields with high purity. Aliphatic and α,β-unsaturated aldehydes which normally show low conversion in the Biginelli reaction, afford the corresponding target compounds in good yields. The feature of this procedure is the ability to tolerate a wide variety of functional groups like ether, nitro, hydroxy, olefin and halide under the reaction conditions. Acid-sensitive aldehydes such as (IIc) also work well without formation of any side products. -(KAMBLE*, V. T.; MULEY, D. B.; ATKORE, S. T.; DAKORE, S. D.; Chin.

Imino Diels-Alder Reactions: One-Pot Synthesis of Tetrahydroquinolines. -The three-component coupling proceeds within short reaction times. The catalyst is reused 4 times without loss of reactivity. -(KAMBLE*, V. T.; DAVANE, B. S.; CHAVAN, S. A.; MULEY, D. B.; ATKORE, S. T.; Chin. Chem. Lett. 21 (2010) 3, 265-268,

This work describes the highly efficient acetylation (acylation) of alcohols with acetic acid for the ester synthesis in the presence of newly designed a new composite zirconium (IV) chloride and magnesium catalyst which is used bimetallic acidic catalyst ZrCl 4 -Mg(ClO 4 ) 2 , which is formed by grinding ZrCl 4 and Mg(ClO 4 ) 2 in the molar ratio of 1:2, respectively. Thus, the powder X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller surface area, and thermogravimetric analysis of the ZrCl 4 , Mg(ClO 4 ) 2 , and non-calcined ZrCl 4 -Mg (ClO 4 ) 2 were recorded. In each case, structural analysis was carried by grinding the catalyst in mortar and pestle. K E Y W O R D S acylation, bimetallic acidic catalyst, scanning electron microscopy (SEM), substituted alcohol, ZrCl 4 -Mg(ClO 4 ) 2

The synthesis of 14-aryl 14H-dibenzo[a,j]xanthenes is achieved by a simple condensation reaction between β-naphthol with aryl or alkyl aldehydes in an effective synergetic catalytic system created by combining basic bleaching earth clay and PEG-600. The advantages of the present method include catalyst recyclability, superior product yield, a shorter reaction time and the avoidance of hazardous reagents. Synthesized xanthene derivatives were also screened for their antibacterial activity against Staphylococcus aureus (MTCC 96) and Pseudomonas aeruginosa (Wild).