Solvent-induced, selective rearrangement of hydrogen cubane-1,4-dicarboxylate to hydrogen cuneane-2,6-dicarboxylate

The rearrangement of cubane-1,4-dicarboxylic acid in water to cuneane-2,6-dicarboxylic acid is presented. The reaction is not a transition metal catalyzed, rather a solvent-promoted transformation, and the reaction proceeds via the semi-dissociated form of the cubane diacid, hydrogen cubane-1,4-dicarboxylate. No other, 1,3-disubstituted cuneane isomer is formed. The reaction is significantly accelerated by the addition of 1 equiv of base, suggesting that the hydrogen cubane-1,4-dicarboxylate ion plays a key role in this new type of rearrangement.