During the last two decades, tetrabutylammonium bromide (TBAB) has gained significant attention as an efficient metal-free homogeneous phase-transfer catalyst. A catalytic amount of TBAB is sufficient to catalyze various alkylation, oxidation, reduction, and esterification processes. It is also employed as an efficient co-catalyst for numerous coupling reactions. It has also acted as an efficient zwitterionic solvent in many organic transformations under molten conditions. In this review, we have summarized the recent developments on TBAB-catalyzed protocols for the efficient synthesis of various biologically promising heterocyclic scaffolds.

Combination of ultrasound and suitable ionic liquid is a powerful tool to carry out diverse organic transformations. In many occasions, this fruitful combination helps to get the desire products without using any further catalysts even at room temperature. Recyclability of ionic liquid makes a protocol cost effective also. The present review deals with the ultrasound‐assisted organic synthesis in various ionic liquids either as catalyst or reaction media.

This review compiles the up to date literatures on the preparations and applications of the transition metal ferrites as an efficient, heterogeneous, magnetically separable nano‐catalyst for the synthesis of diverse bioactive heterocycles.

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A simple, straightforward and efficient method has been developed for the synthesis of (E)-3-(arylimino)indolin-2-one derivatives and (E)-2-((4-methoxyphenyl)imino)- acenaphthylen-1(2H)-one. The synthesis of these biologically-significant scaffolds was achieved from the reactions of various substituted anilines and isatins or acenaphthaquinone, respectively, using commercially available, environmentally benign and naturally occurring organic acids such as mandelic acid or itaconic acid as catalyst in aqueous medium at room temperature. Mild reaction conditions, energy efficiency, good to excellent yields, environmentally benign conditions, easy isolation of products, no need of column chromatographic separation and the reusability of reaction media are some of the significant features of the present protocol.