Crystal structure of a new spiro-polytetrahydrofuran compound with translational pseudosymmetry: rac-(2S,2'S,5'R)-2-methyl-5'-[(1R,2R,5S,5'R)- 1,4,4,5'-tetramethyldihydro-3'H-3,8-dioxaspiro-[bicyclo[3.2.1]octane-2,2'-furan]-5'-yl]hexahydro-[2,2'-bifuran]-5(2H)-one

The title compound, C22H34O6, is a product of oxidation of squalene with the catalytic system RuO4(cat.)/NaIO4. The asymmetric unit contains two crystallographically independent molecules of very similar geometry approximately related by the non-crystallographic translation vector c/2. As a consequence, the average diffracted intensity in the hkl layers with odd l is systematically lower than in the layers with even l. In one molecule, the lactone ring and part of the adjacent tetrahydrofuran ring are disordered over two orientations with refined occupancy ratio of 0.831(10):0.169(10). The crystal structure is mainly governed by van der Waals forces.