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Synthesis 1987; 1987(10): 873-875
DOI: 10.1055/s-1987-28107
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Polarized Ketene Dithioacetals; 53:1 A Facile Synthesis of 2-Aryl-6-methylthio-4H-pyran-4-ones and a Novel Cycloaromatization Reaction

L. W. Singh* , H. Ila, H. Junjappa
  • *Department of Chemistry, North Eastern Hill University, Shillong 793003, Meghalaya, India
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Publication Date:
12 September 2002 (online)

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A facile route to hitherto unreported 2-aryl-6-methylthio-4H-pyran-4-ones 4a-f has been developed by base-catalyzed condensation of acylketene dithioacetal 2 with substituted methyl benzoates 1a-f followed by subsequent ring closure of resulting α-aroylacylketene dithioacetals 3a-f. Acylketene dithioacetal 2 and the corresponding β-methylthioenone 9 are shown to undergo self-condensation and aromatization in the presence of sodium hydride and methylbenzoate in refluxing xylene to give 2, 6-bis(methylthio)-4-hydroxy-acetophenone (6) and 4-hydroxyacetophenone (10) respectively in good yields. A mechanistic pathway for the formation of 6 and 10 via 3 has been described.

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