The title compound, C(20)H(25)NO(4), was synthesized by a Mitsunobu reaction of sinomenine [(9S,13R,14R)-7,8-didehydro-4-hydroxy-3,7-dimethoxy-17-methylmorphinan-6-one] with methanol. The chiral centers were unchanged during the reaction. Intra-molecular C-H⋯O hydrogen bonds result in the formation of six-membered rings.