81748-75-6 Phenanthro(1,2-b)furan-1,7(2H,5H)-dione, 3a,5a,6,8,9,9a,9b,10,11,11a-decahydro-6,6,9a,11a-tetramethyl-, (3aR,5aR,9aR,9bR,11aS)-