(2Z)-4-[8-(acetyloxy)-3,3,11-trimethyl-13-(3-methylbut-2-en-1-yl)-11-(4-methylpent-3-en-1-yl)-7,15-dioxo-3a,4,5,7-tetrahydro-3H,11H-1,5-methanofuro[3,4-g]pyrano[3,2-b]xanthen-1-yl]-2-methylbut-2-enoic acid