Crystal structure of a new spiro-polytetra-hydro-furan compound with translational pseudosymmetry: -(2,2',5')-2-methyl-5'-[(1,2,5,5')-1,4,4,5'-tetra-methyl-dihydro-3'-3,8-dioxa-spiro[bi-cyclo-[3.2.1]octane-2,2'-furan]-5'-yl]hexa-hydro[2,2'-bi-furan]-5(2)-one.

The title compound, CHO, is a product of oxidation of squalene with the catalytic system RuO(cat.)/NaIO. The asymmetric unit contains two crystallographically independent mol-ecules of very similar geometry approximately related by the non-crystallographic translation vector /2. As a consequence, the average diffracted intensity in the layers with odd is systematically lower than in the layers with even . In one mol-ecule, the lactone ring and part of the adjacent tetra-hydro-furan 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.