Crystal structure of (1 R ,3a R ,7a R )-1-{( S )-1-[(2 R ,5 S )-5-(3-hydroxypentan-3-yl)tetrahydrofuran-2-yl]ethyl}-7a-methyl-2,3,3a,4,5,6,7,7a-octahydro-1 H -inden-4-one

The title compound, C 21 H 36 O 3 , contains an oxolane ring, and six defined stereocentres and may serve as a useful synthon for the synthesis of calcitriol analogues. The configurations of the chiral C atoms of the side chain were unambiguously established in the refinement. In the crystal, C—H...O and extremely weak O—H...O hydrogen bonds arising from the sterically hindered alcohol group link the molecules into a three-dimensional network.