2H-cyclopent[d]oxepin-2,4(6H)-dione, 7,8-dihydro-6,6,7,7,8,8-hexamethyl- 6,6,7,7,8,8-hexamethyl-7,8-dihydro-2H-cyclopenta[d]oxepine-2,4(6H)-dione InChI=1/C15H20O3/c1-13(2)9-7-11(16)18-12(17)8-10(9)14(3,4)15(13,5)6/h7-8H,1-6H