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.

Multi-fold Sonogashira coupling: a new and convenient approach to obtain tetraalkynyl anthracenes with tunable photophysical properties.

For the first time, a direct single-step one-pot route to access nine new symmetric tetraalkynylated anthracenes Pd(CHCN)Cl/cataCXium®A catalyzed tetra-fold Sonogashira coupling is reported. Five of these tetraalkynylated anthracenes have been crystallographically characterized, with two of them exhibiting multiple interactions that significantly shorten the inter-planar distances in the solid-state structure. The rich photophysical properties exhibited by these molecules hold immense promise for future applications in sensors and optoelectronic devices.