The mechanochemical, solvent-free Ru­(II)-catalyzed alkenylation of N-heteroaryl arenes with alkynes has been successfully described. A wide spectrum of arenes bearing N-heteroaryl moieties such as imidazo­[1,2-a]­pyridine, imidazo­[1,2-a]­pyrimidine, benzo­[d]­imidazo­[2,1-b]­thiazole, imidazo­[2,1-b]­thiazole, 2H-indazole, 1H-indazole, 1H-pyrazole, and 1,2,4-oxadiazol-5­(4H)-one as a directing group reacted with various substituted alkynes under ball milling in the presence of [Ru­(p-cymene)­Cl2]2, affording dialkenylated products in moderate to good yields. The reaction of 2,3-dihydro­phthalazine-1,4-dione with 1-phenyl-1-propyne afforded a monoalkenylated product. Similarly, reaction of 2-phenyl­imidazo­[1,2-a]­pyridine with aliphatic terminal alkynes produced a monoalkenylated derivative as the major product along with minor amount of dialkenylated product. The developed method exhibited excellent functional group compatibility, broad substrate scope, shorter reaction times, and no external heating. Moreover, the method can be readily scaled-up as demonstrated by gram-scale synthesis of 2-(2,6-bis­((E)­1-phenyl­prop-1-en-2-yl)­phenyl)­imidazo­[1,2-a]­pyridine.

A facile and efficient synthetic method for the construction of C3-hydroxyalkylated imidazo­[1,2-a]­pyridines and indoles by a Zn­(OTf)2-catalyzed Friedel–Crafts hydroxyalkylation of imidazo­[1,2-a]­pyridines and indoles with carbonyl compounds under mechanochemical conditions is reported. Good product selectivity, shorter reaction time, ambient reaction temperature, tolerance of a wide range of functional groups, broad substrate scope, moderate to good yield of products, and scalability are the salient features of the developed methodology.

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A highly efficient copper‐catalyzed three component, one‐pot reaction has been described for the synthesis of imidazo[1,2‐c]quinazolines and benzimidozo[1,2‐c]quinazolines from 2‐(2‐bromophenyl)‐1H‐imidazoles/benzimidazoles using benzyl alcohol or benzylamine as benzaldehyde surrogate and sodium azide as nitrogen source. Various functional groups were well tolerated and desired products were obtained in moderate to good yields. The reaction involves copper‐catalyzed sequential azidation of 2‐(2‐bromophenyl)‐1H‐imidazoles/benzimidazoles through SNAr reaction and reductive amination followed by oxidative condensation with benzyl alcohols or benzylamines. The significant practical advantages of the protocol are utilization of the readily accessible simple substrates, broad substrate scope, and ligand‐free reaction conditions.