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Paper | Regular issue | Vol 34, No. 9, 1992, pp.1803-1812
Published online, 1st January, 1970
DOI: 10.3987/COM-92-6090
A Convenient Synthesis of 3-Hydroxy-4H-pyran-4-one Derivatives Having a Halo or Hydroxy Group at the 5-Position

Hisashi Takao,* Yoshinori Endo, and Tokunaru Horie

*Naruto Research Center, Otsuka Chemical Company, Satoura, Naruto, 772, Japan

Abstract

The reaction of 4,5-epoxy-4-halo-6-methoxy-2-methyltetrahydropyran-3-ones (4b and 5b) in acidic media was examined and the following results were found: The reaction of 4b or 5b with 1% sulfuric acid afforded a mixture of 3,5-dihydroxy-4H-pyran-4-one (1b) and 5-halo-3-hydroxy-4H-pyran-4-one (2b or 3b), but the use of concentrated acid formed the corresponding 5-halo-4H-pyran-4-one (2b or 3b) only. The reaction was applicable for a general method for synthesizing 3,5-disubstituted 4H-pyran-4-ones (1, 2, and 3).