Preparation and Absolute Configuration of (−)-(E)-α-trans-Bergamotenone

The synthesis, absolute configuration, and olfactive evaluation of (−)‐(E)‐α‐trans‐bergamotenone (= (−)‐(1′S,6′R,E)‐5‐(2′,6′‐dimethylbicyclo[3.1.1]hept‐2′‐en‐6′‐yl)pent‐3‐en‐2‐one; (−)‐1), as well as its homologue (−)‐19 are reperted. The previously arbitrarily attributed absolute configuration of 1 and of (−)‐α‐trans‐bergamotene (= (−)‐(1 S,6R)‐2,6‐dimethyl‐6‐(4‐methylpent‐3‐enyl)bicyclo[3.1. 1]hept‐2‐ene; (−)‐2), together with those of the structurally related aldehydes (−)‐3a,b and alcohols (−)‐4a,b, have been rigorously assigned.