Sequential Pd(II)—Pd(0) Catalysis for the Rapid Synthesis of Coumarins.

Department of Chemistry, 1251 Wescoe Hall Drive, 2010 Malott Hall, University of Kansas, Lawrence, Kansas 66045-7582, USA.
The Journal of Organic Chemistry (Impact Factor: 4.64). 09/2005; 70(16):6515-8. DOI: 10.1021/jo050671l
Source: PubMed

ABSTRACT Electrophilic palladium-catalyzed cycloisomerization of brominated aryl propiolates produces brominated coumarins. The brominated coumarins can be diversified by reduction of the Pd(II) catalyst to Pd(0) 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.