Room-Temperature, Copper-Free, and Amine-Free Sonogashira Reaction in a Green Solvent: Synthesis of Tetraalkynylated Anthracenes and Assessment of Their Cytotoxic Potentials.

The multifold Sonogashira coupling of a class of aryl halides with arylacetylene in the presence of an equivalent of CsCO has been accomplished using a combination of Pd(CHCN)Cl (0.5 mol %) and cataCXium A (1 mol %) under copper-free and amine-free conditions in a readily available green solvent at room temperature. The protocol was used to transform several aryl halides and alkynes to the corresponding coupled products in good to excellent yields.