The Biginelli product, dihydropyrimidinone (DHPM) core, and its derivatives are of immense biological importance. There are several methods reported as modifications to the original Biginelli reaction. Among them, many involve the use of different catalysts. Also, among the advancements that have been made to the Biginelli reaction, improvements in product yields, less hazardous reaction conditions, and simplified isolation of products from the reaction predominate. Recently, solid-phase synthetic protocols have attracted the research community for improved yields, simplified product purification, recyclability of the solid support, which forms a special economic approach for Biginelli reaction. The present Review highlights the role of polymer-supported catalysts in Biginelli reaction, which may involve organic, inorganic, or hybrid polymers as support for catalysts. A few of the schemes involve magnetically recoverable catalysts where work up provides green approach relative to traditional methods. Some research groups used polymer−catalyst nanocomposites and polymer-supported ionic liquids as catalyst. Solvent-free, an ultrasound or microwave-assisted Biginelli reactions with polymer-supported catalysts are also reported.

Aminothiazoles and their derivatives are of immense biological importance and have been consistently synthesized via various methods. However, the synthesis of aminothiazole derivatives has some problems such as poor yields, difficult isolation procedures, use of expensive catalysts etc. Recently, polymer or solid-supported synthetic protocols have attracted the attention from the research community because of their easy execution, increased product yields, greater selectivity, simple work-up procedures, and recoverability of the catalysts. In this study, we reported the polymer-supported approaches for the synthesis of differently substituted aminothiazoles.

Nitrogen containing heterocyclic compounds has acquired their remarkable and distinct place in the wide area of organic synthesis due to the broad range of applications. Among them, quinoline motifs have attracted researchers in the synthetic chemistry because of its presence in the large number of pharmacologically active compounds. Different methods for synthesis of quinoline derivatives are reported, among them the Friedlander synthesis have provided comparatively more efficient approach. Many of the reported conventional Friedlander methodologies have some problems such as difficult product isolation procedures, poor yields and use of expensive catalysts etc. Recently, polymer or solid supported synthetic approaches have attracted the attention of researchers because of their easy execution, greater selectivity, increased product yields, simple work-up procedures, recoverability and reusability of the catalysts. In consideration with the advantages of polymer supported synthetic strategies, the proposed review covers the role of polymers in the Friedlander synthesis; 2 which may use polymers of organic, inorganic or hybrid in nature and of nano level as well.

A green and efficient method for the multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones and -thiones using acetic acid supported on activated charcoal as a mild acid catalyst in ethanol under both conventional as well as microwave irradiation conditions has been developed. The catalyst system found more efficient under microwave irradiation conditions than conventional conditions with shorter reaction times and excellent yields.

An impurity formation during the nitro group reduction for the synthesis of Olsalazine Sodium API, which was later explored for the development of a short and efficient manufacturing process for tricaine mesylate is reported here. The highlight of the synthesis is, during the nitro group reduction, the deoxygenation occurs forming the core of tricaine and the leaving mesyloxy group serves as a counter anion furnishing the tricaine mesylate in one step. The reported process here circumvents the need for isolation of the free base and a separate salt formation step, thus it is more economical and efficient.