7-((Tert-butyl(dimethyl)silyl)oxy)-4-(((tert-butyl(dimethyl)silyl)oxy)methyl)-N-hydroxy-6-(5-methyl-2,4-dioxo-3,4-dihydro-1(2H)-pyrimidinyl)-1,5-dioxaspiro[2.4]heptane-2-carboxamide AIDS-161621 AIDS161621 NSC706090