Three-Component Synthesis of Perfluoroalkyl- or Perfluoroaryl-Substituted 4-Hydroxypyridine Derivatives and Their Palladium-Catalyzed Coupling Reactions
couplings. Suzuki reactions at C-4 and C-3 of the pyridine ring proceeded with moderate to high yields. In addition, Suzuki−Miyaura, Stille, or Buchwald−Hartwig couplingreactions have also been studied and afforded the corresponding highly substituted pyridine derivatives. Starting from an arylated propargylic ether the three-componentreaction led to a pentasubstituted 4-hydroxypyridine derivative that
3-alkoxypyridine derivatives. Apt conditions were developed for their conversion into furo[2,3-c]pyridines. Sonogashirareactions of 4-alkoxy-substituted 3-pyridyl nonaflates allowed an access to regioisomeric furo[3,2-c]pyridines. For both types of alkynyl-substituted alkoxypyridinesan alternative method for cyclization employing iodine monochloride furnished iodinated furo[2,3-c]- or furo[3,2-c]pyridines, which