3a,4,13,13a-Tetrahydro-5,6,7,10,11-pentamethoxydibenzo(4,5:6,7)-cycloocta(1,2-c)furan-3(1H)-one 87084-98-8 Dibenzo(4,5:6,7)cycloocta(1,2-c)furan-1(3H)-one, 3a,4,13,13a-tetrahydro-6,7,10,11,12-pentamethoxy-, stereoisomer Neoisostegane