Copper(II)-Mediated Aerobic Synthesis of Imidazo­[1,2‑<i>a</i>]pyridines via Cascade Amino­methylation/Cyclo­isomerization of Alkynes

A single copper­(II)-catalyzed three-component cascade amino­methyla­tion/cyclo­isomeriza­tion of propiolates to form imidazo­[1,2-<i>a</i>]­pyridines was explored. A straightforward method was developed for the practical synthesis of functionalized imidazo­[1,2-<i>a</i>]­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-<i>a</i>]­pyridine-based drug molecules such as Alpidem

A Straightforward Approach toward Multifunctionalized Pyridazines via Imination/Electrocyclization

A facile synthesis of functionalized 3-carbamide pyridazines starting from readily available chlorovinyl aldehydes and oxamic acid thiohydrazides via cascade imination/electrocyclization is reported. In the presence of <i>p</i>-toluenesulfuric acid, various ketones have been efficiently incorporated into the pyridazine derivatives through a two-step sequence involving a Vilsmeier–Haack reaction and imination. The synthetic value of this method has been demonstrated by efficient synthesis of steroidal pyridazines

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-<i>b</i>]­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-<i>b</i>]­benzothiazoles, -[2,1-<i>b</i>]­thiazoles, and -[2,1-<i>b</i>]­[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

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-<i>b</i>]­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-<i>b</i>]­benzothiazoles, -[2,1-<i>b</i>]­thiazoles, and -[2,1-<i>b</i>]­[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