(3S,2′S,5′S,6′R,8′R,10′R)-3-Hydroxy-4-(5′-hydroxy-10′-hydroxymethyl-5′-methyl-1′,7′,9′-trioxadispiro[5.1.5.2]pentadec-2′-yl)but-1-ene

The configurations of four of the six chiral centers in the title compound, C18H30O6, are the same as those in pinnatoxin A, while one is inverted. The configuration of the sixth chiral center, which has no equivalent in pinnatoxin A, has also been determined. The overall mol­ecular structure is stabilized by intra­molecular O—H⋯O hydrogen bonds.