threo-Diethyl 2-ethyl-2-hy­droxy-3-(4-methyl­benzene­sulfonamido)­succinate

The asymmetric unit of the title compound, C(17)H(25)NO(7)S, contains two independent mol­ecules, which are enanti­omers forming a hydrogen-bonded dimer associated with two R (2) (2)(7) patterns. In each mol­ecule, one ethyl group from the two available ethyl ester functional groups is disordered. In one mol­ecule, the ethyl group of the ester function from an α-carb­oxy­lic acid is positionally disordered over two sets of sites with occupancies of 0.66:0.34. In the second mol­ecule, 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.