A straightforward method for the synthesis of functionalized imidazo[2,1-b]thiazoles starting from benzaldehydes, 2-aminothiazoles, and alkynes under copper(I,II) catalysis was developed. The protocol allows the construction of a variety of aryl-substituted imidazo[2,1-b]benzothiazoles, -[2,1-b]thiazoles, and -[2,1-b][1,3,4]thiadiazoles. The reactions were easy to perform affording most of the desired products in 33-93% yields. The intensification of the process in a continuous-flow reactor increases the products' yields up to quantitative.

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A single copper(II)-catalyzed three-component cascade aminomethylation/cycloisomerization of propiolates to form imidazo[1,2-a]pyridines was explored. A straightforward method was developed for the practical synthesis of functionalized imidazo[1,2-a]pyridines from benzaldehydes, 2-aminopyridines, and propiolate derivatives catalyzed by Cu(OAc)2 hydrate in the presence of air. The protocol is marked by excellent yields, functional group tolerance, and, above all, adaptability to synthesize imidazo[1,2-a]pyridine-based drug molecules such as Alpidem.

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