Palladium-Catalyzed Alkynylation of Aryl and Hetaryl Halides: A Journey from Conventional Palladium Complexes or Salts to Palladium/Carbon

Palladium-catalyzed alkynylation of aryl and hetaryl halides has found wide application in the areas of synthetic, hetero-cyclic, and medicinal chemistry. Attempts to introduce the stable and potentially recyclable palladium/carbon has provided an attractive alternative to the homogeneous palladium catalytic process. The present article provides a personal account of the outcome of the use of conventional palladium catalysts versus palladium/carbon, especially under Sonogashira conditions.