(3aS,4R,5S,6S,8R,9S,9aR,10R)-2-[[2-(Diethylamino)ethyl]thio]acetic Acid 6-Ethenyldecahydro-5-hydroxy-4,6,9,10-tetramethyl-1-oxo-3a,9-propano-3aH-cyclopentacycloocten-8-yl Ester (2E)-2-Butenedioate