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Synlett 1991; 1991(8): 595-596
DOI: 10.1055/s-1991-20811
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Facile Regioselective Alkylative Cyclisation: Synthesis of 2-Methyl-4H-thieno[2,3-b] [1]-benzothiopyran-4-one and Thiopyrano[2,3-b] [1]benzothiopyran-5(4H)-one

K. C. Majumdar* , A. T. Khan, S. Saha
  • *Department of Chemistry, University of Kalyani, Kalyani 741 235, W.B., India
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Publication Date:
07 March 2002 (online)

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4-Hydroxy-2H-[1]benzothiopyran-2-thione (1) reacts with propargyl bromide under classical alkylation conditions to give 2-methyl-4H-thieno[2,3-b][1]benzothiopyran-4-one (2) and under phase transfer catalysis conditions to give hitherto unreported thiopyrano[2,3-b][1]benzothiopyran-5(4H)-one (3) in good yield.

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