Synthesis and crystal structure of ocotillol-type metabolites derived from (20R)-protopanaxadiol

Four ocotillol-type (20R)-protopanaxadiol metabolites, (20R,24S)-20,24-epoxy-12β,25-dihydroxdammaran-3-one (M3), and (20R,24R)-20,24-epoxy-12β,25-dihydroxydammarane-3-one (M4), (20R,24S)-20,24-epoxy-3β,25-dihydroxydammaran-12-one (M9) and (20R,24R)-20,24-epoxy-3β,25-dihydroxydammaran-12-one (M10) are synthesised from (20R)-protopanaxadiol. Their structures are confirmed by HRMS, 1H NMR and 13C NMR. Moreover, the absolute configurations of M3 and M4 are confirmed by the X-ray single crystal diffraction.