The title compound, C(14)H(19)NO(5)S, was prepared by nucleophilic addition of the lithium derivative of methyl-phenyl-sulfone to (3S,4R)-3,4-isopropyl-idene-dioxy-pyrroline 1-oxide. There are four mol-ecules in the asymmetric unit. The crystal structure determination confirms the configuration of the chiral centres as 2R,3S,4R. In the crystal, pairs of O-H⋯N hydrogen bonds link the mol-ecules into dimers.