7H-furo[3,2-g][1]benzopyran-7-one, 9-[(3-methyl-2-butenyl)oxy]- 9-[(3-methylbut-2-en-1-yl)oxy]-7H-furo[3,2-g]chromen-7-one InChI=1/C16H14O4/c1-10(2)5-7-19-16-14-12(6-8-18-14)9-11-3-4-13(17)20-15(11)16/h3-6,8-9H,7H2,1-2H