1,5-dimethyl-bicyclo<3.3.0>octandion, 1,5-Dimethylbicyclo<3.3.0>octan-3,7-dione, cis-3a,6a-Dimethyltetrahydropentalene-2,5(1H,3H)-dione, 1,5-Dimethylbicyclo<3.3.0>octan-3,7-dion, rel-(3aR,6aR)-3a,6a-diMethyl-octahydropentalene-2,5-dione, 3A,6A-DIMETHYLPERHYDROPENTALENE-2,5-DIONE, 1,5-dimethylbicyclo<3.3.0>octane-3,7-dione, cis-tetrahydro-3a,6a-dimethylpentalene-2,5(1H,3H)-dione, cis-1,5-dimethylbicyclo<3.3.0>octane-3,7-dione