2-((2S,3R,5R)-3-hydroxy-2-methyl-5-((4aR,5aS,6aR,7aS,10S,11aR,12R,13aS,14aR,15aS)-2,2,5a,10,12-pentamethylhexadecahydro-[1,3]dioxino[4'',5'':5',6']pyrano[2',3':5,6]pyrano[3,2-b]pyrano[2,3-f]oxepin-10-yl)tetrahydrofuran-2-yl)ethyl pivalate