1H-Bis(1)benzopyrano(3,4-b:6'5'-e)pyran-7,13-dione, 2,3-dihydro-9,10-dimethoxy-3,3-dimethyl- 2,3-Dihydro-9,10-dimethoxy-3,3-dimethyl-1H-bis(1)benzopyrano(3,4-b:6'5'-e)pyran-7,13-dione 4440-77-1