Acid-catalysed dehydration of withanolide E, a 14α,17β,20αF-trihydroxysteroid; a revision
Abstract
The structure of the products obtained by treatment of (17S,2OS,22R)-5β,6β-epoxy-14α,17,20-trihydroxy-1-oxowitha-2,24-dienolide (withanolide E) with sulphuric acid in acetone solution has been reinvestigated. Whereas the major component is indeed (17S,20S,22R)-5α,6β,17,20-tetrahydroxy-1-oxowitha-2,14,24-trienolide, the minor component which was previously considered to be the Δ8(11) isomer of the latter, has now been shown to be (17S,22R),14α,20ξ-epoxy-5α,6β,17-trihydroxy-1-oxowitha-2,24-dienolide. The configuration at C-20 is most probably 20R.