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Paper | Regular issue | Vol 60, No. 4, 2003, pp.825-831
Published online, 3rd March, 2003
DOI: 10.3987/COM-02-9685
Benzopyrans. Part 44. Synthesis of 3-(4-Oxo-4H-1-benzopyran-2-yl)indolizines

Chandra Kanta Ghosh,* Sumit Kumar Karak, and Amarendra Patra

*Department of Biochemistry, CalcuttaUniversity, Kolkata 700019, India


The pyridinium methylid (5), generated from 1-(4-oxo-4H-1-benzopyran-2-yl)methylpyridinium iodide (4) in the presence of a base, undergoes [3+2] cycloaddition with dimethyl acetylenedicarboxylate and ethyl propiolate, the cycloadducts rapidly aromatising to the indolizines (8) and (9), respectively. Similar cycloaddition of 5 with ethyl acrylate and acrylonitrile is also followed by dehydrogenation giving respectively the indolizines (9) and (10).