(1R,2S,3R,4R,5S,6S)-2,4,5,6-tetrahydroxycyclohexane-1,3-diyl (1S,1'S,4R,4'R)-bis(4,7,7-trimethyl-3-oxo-2-oxabicyclo[2.2.1]heptane-1-carboxylate)