Caro’s acid-silicagel was found to be a mild and effective catalyst for the one –pot multicomponent condensation of benzyl, aldehydes and ammonium acetate used for synthesis of 2, 4, 5-trisubstituted imidazole derivatives under solvent–free conditions. This catalyst has several advantages such as simple work-up, low cost and reusability.

An efficient one-pot condensation for the synthesis of 1,8-dioxo-octahydroxanthene is  achieved through a condensation of aryl aldehydes and 5,5-dimethyl-1,3-cyclohexandione in the presence of  NBS. This method enjoys several advantages such as low cost, simple work up procedure and safe reaction condition. In addition, water was chosen as a green solvent.

In the present of methylimidazolium hydrogen sulfate, the synthesis of arylidene heterobicyclic pyrimidinones is studied by condensation of aromatic aldehyde, cyclopentanone, and urea or thiourea. Using solvent-free conditions, non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are the advantages of this method.

Two  simple  protocols  for  the  synthesis  of  1,  2,  4,  5-   tetrasubstitutedimidazoles  using  nano-SPA  as  a  reusable,  eco-   friendly,  inexpensive,  and  efficient  catalyst  are  reported.  Short   reaction  times,  high  yields,  scale-up  and  easy  workup  are  the   advantages of these protocols.

An effective one-pot synthesis of dihydropyrimidinonoes in solvent free conditions using CuCl2 as an inexpensive and readily available reagent through Biginelli condensation reaction of aldehyde derivatives, 1,3-dicarbonyl compounds and urea is described. Excellent yields, short reaction times for formation of the products and simple work-up are attractive features of this green prot...

In this study, an efficient and green process for the synthesis of dihydropyrimidin-2(1H)-ones from aromatic benzaldehydes, ethyl acetoacetate and urea using Al-MCM-41 as heterogeneous catalyst and microreactor under solvent-free conditions has been developed. The advantages of this method are easy work-up procedure, regeneration of the catalyst, clean and neutral reaction conditions.

In this study, an efficient and green process for the synthesis of dihydropyrimidin-2(1H)-ones from aromatic benzaldehydes, ethyl acetoacetate and urea using Al-MCM-41 as heterogeneous catalyst and microreactor under solvent-free conditions has been developed. The advantages of this method are easy work-up procedure, regeneration of the catalyst, clean and neutral reaction conditions.

La(OAc)3 has been used as an efficient catalytic system for the synthesis of quinoxalines. This method provides several advantages over methods that are currently employed such as a simple work-up, mild reaction conditions, good to excellent yields, and a process to recover and reuse the catalyst for five cycles with consistent activity.

An one-pot method has been developed for the synthesis of azo dyes via sequential diazotization–diazo coupling of aromatic amines with coupling agents at room temperature in the presence of Bi(NO3)3. 5H2O. Short reaction times, high yields, a clean process, simple methodology, easy work-up and green ‎conditions are advantages of this protocol.‎

Poly(4-vinylpyridine)-supported copper iodide nanoparticles is reported as a new, green and recyclable catalyst for the synthesis of aryl-14H-dibenzo [a-o] xanthenes under solvent-free conditions. This catalyst can be recovered by simple filtration and recycled up to 8 consecutive runs without any loss of their efficiency.