Unexpected Tethering in the Synthesis of Methyl‐Substituted Acetyl‐1‐oxaspiro[4.5]­decanes: Novel Woody–Ambery Odorants with Improved Bioavailability (Eur. J. Org. Chem. 2/2008)
The cover picture shows the X-ray crystal structure of a spirocyclic analog of the woody-ambery odorant Iso Gamma, in which the polarity of the γ-double bond is mimicked by the oxygen atom of the spiroannulated 3,3-dimethyltetrahydrofuran-2-yl moiety. The log Pow value thereby improves from 5.7 to 3.2, so that this pleasant woody-ambery odorant, which is reminiscent of Iso E Super with additional agrestic, conifer-type facets of Cashmeran, can indeed be considered the first water-soluble perfumery raw material of the woody-ambery family. According to the European REACH regulations, it is thus classified as being bioavailable and regarded to be nonpersistent in the environment. To emphasize on the paradox of wood being water-soluble, the wooden ORTEP model seems to dissolve into incense smoke that floats like streaks in water above a wood grain that warps like the ground of the ocean. But besides the interesting physical and olfactory properties of the target structure, P. Kraft and K. Popaj also report on an unprecedented tethering effect that was discovered in the course of synthetic attempts towards this and related structures by Diels–Alder reactions, on p. 261 ff.