tert-butyl 2-((4R,6R)-6-(acetoxymethyl)-2,2-dimethyl-1,3-dioxan-4-yl)acetate compound with tert-butyl 2-((4R,6S)-6-(acetoxymethyl)-2,2-dimethyl-1,3-dioxan-4-yl)acetate and tert-butyl 2-((4S,6S)-6-(acetoxymethyl)-2,2-dimethyl-1,3-dioxan-4-yl)acetate (2:1:1)