Recent Expedition in Pd-Catalyzed Sonogashira Coupling and Related Processes(dagger)

Comprehensive SummarySonogashira cross-coupling protocol, typically showing the reaction between aryl/vinyl halide and terminal alkyne, has been a widely used protocol for constructing C(sp(2))-C(sp) bond. The resulting internal alkynes are highly versatile for reaching differently functionalized alkyne-containing scaffolds or serving as valuable synthetic synthons to many other functional groups. It is worth noting that products originated from this coupling reaction are mostly applicable to be transformed into corresponding Z-alkene, alkane, or heterocyclic moieties in natural product syntheses. The reaction conditions and catalyst systems are able to be tweaked in order to facilitate the activation of steric hindered and/or electron-rich electrophiles. Pd-catalyzed copper-free Sonogashira coupling reaction has caught increasing attention as the improved method can be more environmentally friendly. What is more, the conditions of the coupling reaction can be readily amended to allow the fusion of other carbonylation or decarboxylation step in the catalytic cycle, and thus allow more complex yet versatile convergent synthesis to proceed in an operationally simple one-pot manner.