A mechanochemical method for the preparation of synthetically useful 2-arylindoles is developed using Pd(II) as the catalyst in the absence of phosphine ligands in a ball-mill. The developed protocol is highly C-2 selective and tolerant of structural variations with electron-rich and electron-deficient substituents both in indoles and iodoarenes. Arylation is possible in both unprotected indoles and Nprotected indoles with the electron-donating group with the former substrate being relatively slower to react and little less yielding. Indoles with a deactivated five-membered ring could also take part in the reaction with ease. The scalability of the reaction was demonstrated by conducting the reaction in the gram scale. In general, the reactions were achieved in a shorter time than the conventional methods.

A catalyst‐free, greener and highly efficient method for the synthesis of a series of quinoxaline derivatives involving simple liquid assisted hand‐grinding in a mortar and pestle has been developed. The mechanochemical agitation under LAG was sufficient enough for the smooth condensation of both aromatic and heteromatic 1,2‐diamines with a variety of 1,2‐dicarbonyl compounds to afford the corresponding quinoxalines in high yields. Several of these quinoxaline derivatives inhibit the growth of Mycobacterium smegmatis in moderate to good effect. Simple substitution in the quinoxaline ring was found to be more effective in antibacterial agents than bulky substitution. In particular, pyrido[2,3‐b]pyrazines with an additional N‐atom in the scaffold showed better activity than others. Overall, the key advantages of this method are simplicity of operation, catalyst‐free condition, solvent‐less synthesis, low E‐factor, cleaner reaction profile, devoid of work‐up step, easy purification and shorter reaction times, and the new series of pyrido[2,3‐b]pyrazines are good antibacterial agents against M. smegmatis.

An efficient and environmentally sustainable method for the synthesis of imidazo[1,2- a ]pyridine derivatives by domino A 3 -coupling reaction catalyzed by Cu(II)–ascorbate was developed in aqueous micellar media in the presence of sodium dodecyl sulfate (SDS). The catalyst, a dynamic combination of Cu(II)/Cu(I), was generated in situ in the reaction mixture by mixing CuSO 4 with sodium ascorbate and aided a facile 5- exo -dig cycloisomerization of alkynes with the condensation products of 2-aminopyridines and aldehydes to afford a variety of imidazo[1,2- a ]pyridines in good overall yields. A simple experimental setup, water as the “green” medium, and inexpensive catalyst and auxiliary are some of the merits of this protocol.

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An efficient, catalyst free mechanochemical route to 2-aryl benzothiazoles and both 2- and 1,2-disubstituted benzimidazoles has been developed via a simple mortar–pestle grinding method.