In the title compound, rel-(2R,3S,1'R,2'S,5'S,7'S)-3-allyl-2-(2'-hydroxy-7'
--trimethylsilylbicyclo[3.3.0]octan-2'-yl)cyclopentanone, C19H32O2Si, the t
wo rings of the bicyclo[3.3.0]octane unit adopt an envelope conformation an
d the cyclopentanone ring is in a twist conformation. In the crystal, molec
ules related by a center of symmetry are hydrogen bonded to form dimers.