Sterols of the cultured dinoflagellate Pyrocystis lunula
摘要:
Eighteen components of the sterol fraction of Pyrocystis lunula have been identified. In addition to 4 alpha-methyl sterols (typical dinoflagellate sterols), regular sterols, both with a saturated and delta 5-unsaturated skeleton, were isolated, together with delta 4-3-keto steroids including the hitherto unknown 23,24R-dimethyl-4,22E-cholestadien-3-one.
Using a Claisen ortho-ester rearrangement, the biogenetically important marinesterol dinosterol and its C-24 epimer were synthesized stereospecifically by a sequence which is also attractive for selective isotope labelling in the sidechain.