Three new apo-tirucallols with six-membered hemiacetal from Meliaceae

Three new apo-tirucallols, 1α,7α-diacetoxyl-17α-20S-21,24-epoxy-apotirucall-14-ene-3α,23R,24S,25-tetraol (), 7α-acetoxyl-17α-20S-21,24-epoxy-apotirucall-14-ene-3α,23R,24S,25-tetraol (), 7α-acetoxyl-17α-20S-21,24-epoxy-apotirucall-14-en-3-one-23R,24S,25-triol () were obtained from the plants of the family Meliaceae. Their configurations were elucidated on the basis of extensive 1D and 2D NMR techniques in CD3OD solution. The equilibrium of the six-membered ring hemiacetal at side chain is also discussed. Finally, the stereochemistry of compound was demonstrated by X-ray crystallography.