Synthesis of bivalent ligands of β-carboline-3-carboxylates via a palladium-catalyzed homocoupling process

The first synthesis of bivalent ligands of β-carboline-3-carboxylates has been achieved from β-carboline-3-carboxylate tert-butyl ester (βCCt) via Sonogashira and palladium-catalyzed homocoupling processes. The Boc protected intermediate, an iodo-β-carboline-3-carboxylate, was employed to provide a general entry into a series of bivalent ligands structurally similar to βCCt.