Structural and conformational study of (+/-) (6S, 7R)-3-aza-7-iodo-1-oxaspiro[5.5]undecan-2-one

The single crystal X-ray structure of racemic (6S, 7R)-3-aza-7-iodo-1-oxasp iro[5.5]undecan-2-one 1 shows, in the solid state, a cyclohexane ring in a chair conformation with the iodine and the oxygen substituents in axial pos itions. The oxazinone ring presents a sofa like conformation (conformation 1). Theoretical and experimental conformational analyses also reveal the pr esence in solution of, at least, two more conformations: one with the inver ted chair in the cyclohexane (conformation 3) and the other with the invert ed sofa in the oxazinone (conformation 2). (C) 2000 Elsevier Science B.V. A ll rights reserved.