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Synfacts 2007(7): 0694-0694
DOI: 10.1055/s-2007-968685
DOI: 10.1055/s-2007-968685
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York
Base-Catalyzed 2H-Chromene Synthesis from Salicylaldehydes and Allenes
L.-Z. Dai, Y.-L. Shi, G.-L. Zhao, M. Shi*
Shanghai Institute of Organic Chemistry, P. R. of China
Further Information
Publication History
Publication Date:
22 June 2007 (online)
Significance
The synthesis of 2H-chromenes by the reaction of salicylaldehydes with allenes under very mild basic conditions is reported. Perhaps of further synthetic interest, two isomeric chromenes A and B are produced depending on workup conditions: using chromatography on silica gel leads to the isolation of isomer A; in contrast, chromatography on neutral Al2O3 affords chromene B. Ready conversion of isomer B into A was achieved. Mechanistic proposals are provided. The scope and limitations of this method have been insufficiently tested.