(3aR,7R,7aR)-2,2-Diethyl-3a,6,7,7a-tetrahydro-7-[(methylsulfonyl)oxy]-1,3-benzodioxole-5-carboxylic Acid Ethyl Ester is an analog of (1R,5S,6S)-rel-5-(1-Ethylpropoxy)-7-oxabicyclo[4.1.0]hept-3-ene-3-carboxylic Acid Methyl Ester (E925665) which is an intermediate in the synthesis of neuraminidase inhibitors.