(2R,3R)-1,4-Dioxaspiro[4.4]nonane-2,3-dicarboxylic and (2R, 3R)-1,4-dioxaspiro[4.5]decane-2,3-dicarboxylic acids
The title compounds, C9H12O6 and C10H14O6, were formed by careful hydrolysis of the corresponding diethyl esters. Their single crystals were grown from an ethyl acetate/hexane mixture. Crystals of both compounds have monoclinic (P2(1)) symmetry with a single molecule in the asymmetric unit. Both crystal structures are very similar and display four -CO-OH center dot center dot center dot O=C(OH)-hydrogen bonds, forming a two-dimensional double-layered framework.