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Synfacts 2011(1): 0017-0017
DOI: 10.1055/s-0030-1259194
DOI: 10.1055/s-0030-1259194
Synthesis of Heterocycles
© Georg Thieme Verlag
Stuttgart ˙ New York
Palladium-Catalyzed Annulation Route to 6H-Benzo[c]chromenes
R.-J. Li, S.-F. Pi, Y. Liang*, Z.-Q. Wang, R.-J. Song, G.-X. Chen, J.-H. Li*
Hunan Normal University, Changsha, P. R. of China
Further Information
Publication History
Publication Date:
21 December 2010 (online)
Significance
Reported is the synthesis of 6H-benzo[c]chromenes 3 via the palladium-catalyzed annulation of 2-(2-iodophenoxy)-1-substituted ethanones 1 with arynes generated in situ from 2. Both EDGs and EWGs were uniformly tolerated on the 2-iodophenoxy starting material. A lower yield was observed for an aliphatic ketone (R² = Me, 30% yield) compared to the aromatic ketones. Application of substituted aryne precursors led to an equimolar mixture of regioisomers as expected. Two possible mechanisms are presented, although proof for the formation of the aryne (e.g. by trapping with furan) is lacking.