tert-Butyl (4R-ctert-butyl 2-((4R,6S)-2,2-dimethyl-6-(((5-methyl-1,3,4-thiadiazol-2-yl)sulfonyl)methyl)-1,3-dioxan-4-yl)acetate؛ D4.is)-6-formaldehydel-2,2-dimethyl-1,3-dioxane-4-acetate