1H-7,9b-Methanoazuleno[1,8-cd]pyran-1,3,8-triol,3,3a,4,5,5a,6,7,8-octahydro-6,6-dimethyl-, 1,3-diacetate, [1S-(1a,3b,3ab,5aa,7b,8a,9bb)]-