rel-Methyl (3R,3aR,4aS,5S,7R,8R,8aS,9aS)-5-bromododecahydro-3-isopropyl-8,9a-dimethyl-10-oxo-4a,8-(epoxymethano)-4aH-benz[f]indene-7-carboxylate (1) and rel-methyl (3R,3aS,4aS,5S,7R,8R,8aS,9aS)-5-bromododecahydro-3-isopropyl-8,9a-dimethyl-10-oxo-4a,8-(epoxymethano)-4aH-benz[f]indene-7-carboxylate (2