(7R,8S,9S,12S)-1-(4-Chloro-benz-yloxy)-13,14-didehydro-12-hy-droxy-2,13-dimeth-oxy-N-methyl-morphinane.

The title compound, C(26)H(30)ClNO(4), a sinomenine derivative, has five six-membered rings, two of which are aromatic, with a dihedral angle of 34.13 (20)° between these. The N-containing ring and the fourth ring exhibit chair conformations, while the fifth ring approximates an envelope conformation. A single inter-molecular O-H⋯N hydrogen-bonding inter-action gives a one-dimensional chain structure which extends along the a axis. The absolute configuration for the mol-ecule has been determined.