(2S,3R,4aS,5aR,6R,7aS,8aR,10S,11R,12aS,13aR,14aS,16aR)-3-((tert-butyldimethylsilyl)oxy)-2,6,12a,16a-tetramethyl-11-(prop-1-en-2-yl)-2-vinyloctadecahydro-2H-pyrano[2',3':5,6]pyrano[3,2-b]pyrano[2',3':6,7]oxepino[2,3-f]oxepin-10-ol