Oxycodone N-oxide.

The title compound, (5R,9R,13S,14S,17R)-14-hydroxy-3-methoxy-17-methyl-4,5-epoxymorphinan-6-one N-oxide, C(18)H(21)NO(5), has been prepared in a diastereomerically pure form by the reaction of oxycodone with 3-chloroperbenzoic acid and subsequent crystallization of the product from chloroform. The crystal packing shows that the molecule exhibits intramolecular O-H···O [D···A = 2.482 (2) Å] hydrogen bonding. In addition, there are weak intermolecular C-H...O interactions which, along with van der Waals forces, stabilize the structure. The new chiral center at the 17-position is demonstrated to be R.