The structure and absolute configuration of (−)‐β‐Sesquiphellandrene ((−)‐1a) is shown to be (6S)‐2‐methyl‐6‐[(1′R)‐4‐methylidenecyclohex‐2‐enyl]hept‐2‐ene by stereospecific synthesis of its enantiomer ((+)‐1a) and of a further (6S,1′S)‐diastereoisomer ((+)‐1b). Characteristic spectroscopic differences in both diastereoisomeric series are discussed.

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Esterification of a single diastereomer of 2‐(4‐methylene­cyclohex‐2‐enyl)propanol, (II), with (1R,4S)‐(+)‐camphanic acid [(1R,4S)‐4,7,7‐trimethyl‐3‐oxo‐2‐oxabicyclo[2.2.1]heptane‐1‐carboxylic acid] leads to the crystalline title compound, C20H28O4. The relative configuration of the camphanate was determined by X‐ray diffraction analysis. The outcome clarifies the relative and absolute stereochemistry of the naturally occurring bisabolane sesquiterpenes β‐turmerone and β‐sesquiphellandrene, since we have converted (II) into both natural products via a stereospecific route.

Stereoselective hydroboration of (−)‐isopulegol and subsequent fractional crystallization furnishes the title compound, C10H20O2. The relative configuration of the stereogenic centres has been assigned by means of X‐ray diffraction analysis since the monoterpenediol is employed as a versatile chiral building block in stereospecific natural product synthesis.

The crystal structure of the title compound, C(10)H(20)O(2), was published [Korner et al. (2000). Acta Cryst. C56, 74-75] with an erroneous position for an hydroxy H atom. This has now been corrected and leads to a more sensible hydrogen-bonding scheme.