4,6a-Bis((acetyloxy)methyl)-9a-methyl-3-oxo-1a,1b,3,5,6,6a,7a,9a-octahydrodioxireno[2',3':5,6:2',3':9,10]cyclodeca[1,2-b]furan-5-yl 2-methylpropanoate AIDS-144426 AIDS144426 NSC666857