(3aS,5aR,6R,9aS,9bR,11aS)-2,6,9a-Trimethyl-11-methylene-1-oxo-tetradecahydro-cyclobuta[d]phenanthrene-6-carboxylic acid methyl ester

rac-methyl (3aR,5aS,6S,9aR,9bS,11aR)-2,6,9a-trimethyl-11-methylenedodecahydro-2H,10H-spiro[cyclobuta[d]phenanthrene-1,2'-[1,3]dioxolane]-6-carboxylate