A novel C2-symmetric bis-sulfoxide 1 was synthesized as a chiral auxiliary for asymmetricdesymmetrization of meso-1,2-diols. cis-Cyclohexane-1,2-diol and cis-cyclopentane-1,2-diol were desymmetrizedvia acetalization with 1 followed by base-promoted acetal cleavage with high diastereoselectivity (>96% d.e.).