Perhydroxylated 1,7-Dioxaspiro[5.5]undecanes ("Spiro Sugars"): Synthesis, Stereochemistry, and Structure

As spiro sugars is an apt way of considering perhydroxylated 1,7-dioxaspiro[5.5]undecanes-a class of compounds which has not been found in nature up to now. The crystal structure of such a spiroacetal, in which the two pyran rings show the β-D-manno configuration, is depicted. Note that the all-trans arrangement of C-6, C,-5, O_pyr , C_spiro , O_pyr^' , C-5', and C-6' does not allow any of the stereoelectronic effects that are typical of carbohydrates.