(2R,3R)-1,4-Dioxaspiro[4.4]nonane-2,3-dicarboxylic Acid Diethyl Ester is an intermediate used in the synthesis of (2S,3R)-2-Methyl-1,2,3,4-butanetetrol (M295075), which is a secondary organic aerosol formed through photooxidation of isoprene. It was identified as a glucide in methanol extracts of Carum ajowan fruit.