(4aR,5aS,6aR,7aS,9R,10S,11aR,13aS,14aR,15aS)-9-(benzyloxy)-10-((benzyloxy)methyl)-2,2-di-tert-butyl-6a-methylhexadecahydro-[1,3,2]dioxasilino[4'',5'':5',6']pyrano[2',3':5,6]pyrano[3,2-b]pyrano[2,3-f]oxepine