Structure of an ether dimer of deoxydihydroqinghaosu, a potential metabolite of the antimalarial arteether

C30H49O7, Mr = 518.69, triclinic, P1, a = 9.013 (2), b = 10.520 (2), c = 15.187 (3) A, alpha = 93.3 (2), beta = 93.73 (1), gamma = 95.88 (2) degrees, V = 1426.2 (5) A3, Z = 2, Dx = 1.21 Mg m-3, lambda(Cu K alpha) = 1.54178 A, mu = 0.65 mm-1, F(000) = 564, T = 295 K, final R = 0.043, wR = 0.042 for 3842 observed reflections. The dimer is formed such that the deoxyarteether moieties are cis to one another. Attempts to determine the absolute configuration of the molecule were inconclusive so the conformation corresponding to that found for qinghaosu was used for the refinement. Both halves of the dimer have the same chirality with five of the seven asymmetric carbons having an S conformation and two (C5 and C6) having an R conformation.