tert-butyl 2-((3aR,6S,7S,7aR)-7-((tert-butyldimethylsilyl)oxy)-2',2'-dimethyl-2-oxotetrahydrospiro[pyrano[3,4-d]oxazole-6,4'-[1,3]dioxolan]-3(2H)-yl)acetate

(3aR,6S,7S,7aR)-7-((tert-butyldimethylsilyl)oxy)-2',2'-dimethyl-3-tosyltetrahydrospiro[pyrano[3,4-d]oxazole-6,4'-[1,3]dioxolan]-2(3H)-one