1H-3a,7-Methanoazulene-6,9-diol,3-[[(1,1-dimethylethyl)dimethylsilyl]oxy]octahydro-8-methyl-5-(2-propenyl)-, 9-benzoate, (3a,3ab,5b,6b,7b,8b,8aa,9R*)-(±)-