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Synfacts 2009(7): 0720-0720  
DOI: 10.1055/s-0029-1217386
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Pyrano[2,3-c]coumarins via Intramolecular Domino Reactions

Contributor(s): Victor Snieckus, Toni Rantanen
M. J. Khoshkholgh, M. Lotfi, S. Balalaie*, F. Rominger
Toosi University of Technology, Tehran, Iran and Universität Heidelberg, Germany
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Publication History

Publication Date:
22 June 2009 (online)

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Significance

The domino Knoevenagel hetero-Diels-Alder reaction of O-propargylated salicyl­aldehydes and 4-hydroxycoumarins is reported to lead to pyrano[2,3-c]coumarins and pyrano[2,3-c]chromones in the presence of CuI as a Lewis acid catalyst. The reaction is quite selective towards product A. The yields range from moderately good to very good, but the yields refer to the yield of either pure A (when selectivity = 100:0) or that of a mixture. It seems it was not possible to separate A and B chromatographically. Substrate scope was poorly studied.