Sequential Pd(II)−Pd(0) Catalysis for the Rapid Synthesis of Coumarins
摘要:
Electrophilic palladium-catalyzed cycloisomerization of brominated aryl propiolates produces brominated coumarins. The brominated cournarins can be diversified by reduction of the Pd(II) catalyst to Pd(O) followed by Suzuki, Sonogashira, Heck, or Hartwig-Buchwald coupling. Thus, a single loading of precatalyst can be used to conduct sequential reactions, allowing the synthesis of functionalized coumarins. Extension of this methodology toward the synthesis of coumarin libraries is discussed.