The asymmetric unit of the title compound, C(17)H(25)NO(7)S, contains two independent mol-ecules, which are enanti-omers forming a hydrogen-bonded dimer associated with two R(2) (2)(7) patterns. In each mol-ecule, one ethyl group from the two available ethyl ester functional groups is disordered. In one mol-ecule, the ethyl group of the ester function from an α-carb-oxy-lic acid is positionally disordered over two sets of sites with occupancies of 0.66:0.34. In the second mol-ecule, it is the ethyl group in the γ-ester function that is disordered over two sets of sites with occupancies of 0.58:0.42.