La configuration du «carquéjol» (Isopropényl‐2‐méthylène‐3‐cyclohexène‐4‐ol) et la conformation privilégiée de l' ortho‐néo‐isomenthol

The complete stereochemistry of carquejol (= cis‐(2S)‐isopropenyl‐3‐methylene‐cyclohex‐4‐en‐1‐ol) is described. The absolute configuration was obtained from the circular dichroism of the corresponding 0‐menthones. Carquejol and its reduction products, having the all‐cis configuration, appear from NMR. measurements to prefer a conformation having the hydroxyl (or acetoxyl) group axial and the isopropenyl (or isopropyl) group equatorial, even when the exo‐methylene group is reduced to methyl. The mass spectra of the compounds are briefly described.