Visible-light-induced decarboxylative alkynylation of carboxylic acids in batch and continuous flow

A green efficient photoredox-catalyzed decarboxylative alkynylation of carboxylic acids with alkynyl bromides has been developed. This broadly applicable protocol is presented wherein α-amino, aliphatic and α-oxy acids are converted into useful alkynylation products. The commercially-available organic photocatalyst 4CzIPN is used as the photocatalyst, organic base DBU is utilized as the base, and DMSO serves as solvent. This strategy features mild conditions, is metal-free, and is environmentally friendly. The batch and continuous-flow protocols described were applied to obtain a broader substrate scope of functionalization (more than 50 examples). Furthermore, we demonstrate that the use of microflow technology enhanced and intensified the reaction process, achieving significantly reduced reaction times (i.e., 10 ​min of residence time).