Intermediates for the preparation of gamma-pyrones
申请人:Pfizer Inc.
公开号:US04387235A1
公开(公告)日:1983-06-07
2-methyl-3-hydroxy-4H-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydropyran intermediate is substantially complete. Other valuable related gammapyrones are prepared in analogous manner from appropriate alcohols.
3,4-Dihalo-tetrahydrophyran-5-one useful as intermediates for the
申请人:Pfizer Inc.
公开号:US04368331A1
公开(公告)日:1983-01-11
(2-methyl-3-hydroxy-4h-pyran-4-one is prepared by contacting 1(2-furyl)-1-ethanol in aqueous solution with two equivalents of a halogen oxidant at room temperature and then heating until the hydrolysis of the formed 4-halo-dihydro-pyran intermediate is substantially complete. Other valuable related gamma-pyrones are prepared in analogous manner from appropriate alcohols.
A Convenient Synthesis of 3-Hydroxy-4H-pyran-4-one Derivatives Having a Halo or Hydroxy Group at the 5-Position
作者:Hisashi Takao、Yoshinori Endo、Tokunaru Horie
DOI:10.3987/com-92-6090
日期:——
The reaction of 4,5-epoxy-4-halo-6-methoxy-2-methyl-tetrahydropyran-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).