Synthesis of Imidazo[2,1‑<i>b</i>]thiazoles via Copper-Catalyzed A³‑Coupling in Batch and Continuous Flow

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.