(3R,4S)-4-(1,3-benzodioxol-5-ylcarbonyl)-3-[(R)-1-(1,3-benzodioxol-5-yl)-1-hydroxymethyl]tetrahydro-2-furanone

threo-diethyl 2,3-bis-(3,4-methylenedioxybenzoyl)butane-1,4-dioate