Enantioselectivity in Odor Perception

The 3‐methyl‐4‐(tricyclo[5.2.1.0 2,6 ]dec‐4‐en‐8‐ylidene)butan‐2‐ols (= Fleursandol ® ; rac ‐ 10 ), a new class of sandalwood odorants, were synthesized in their enantiomerically pure forms by use of tricyclo[5.2.1.0 2,6 ]dec‐4‐en‐8‐ones 17 and ent ‐ 17 and (tetrahydro‐2 H ‐pyran‐2‐yl)‐protected 4‐bromo‐3‐methylbutan‐2‐ols 22 and ent ‐ 22 as starting materials ( Schemes 2–4 ). Only four of 16 possible stereoisomers of rac ‐ 10 possess the typical, very pleasant, long‐lasting sandalwood odor ( Table 1 ). The (2 S ,3 R ,4 E ,1′ R ,2′ R ,6′ R ,7′ R )‐isomer ent ‐ 10a is by far the most important representative, with an odor threshold of 5 μg/l in H 2 O.