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Synfacts 2010(5): 0525-0525
DOI: 10.1055/s-0029-1219717
DOI: 10.1055/s-0029-1219717
Synthesis of Heterocycles
© Georg Thieme Verlag
Stuttgart ˙ New York
Ligand-Free Cyclocarbonylation of ortho-Iodophenols and Acetylenes to Chromones
Q. Yang, H. Alper*
University of Ottawa, Canada
Further Information
Publication History
Publication Date:
22 April 2010 (online)
![](https://www.thieme-connect.de/media/synfacts/201005/lookinside/thumbnails/10.1055-s-0029-1219717-1.jpg)
Significance
Reported is the palladium-catalyzed synthesis of chromones via cyclocarbonylation of ortho-iodophenols followed by reaction with terminal acetylenes in an ionic liquid. Other palladium sources and ionic liquids were briefly investigated but afforded either lower yields or required higher CO pressures than those shown. Lowering the catalyst loading (1 mol%) and recycling the ionic liquid/active catalyst mixture were investigated, with a slight decrease in yield observed in both cases (95 to ˜80%). The substrate scope was well studied in terms of alkyne, not so with respect to the iodophenol counterpart.