Configuration-Odor Relationships in 5β-Ambrox

The four possible A/B cis-fused diastereoisomers of Ambrox ® have been synthesized and their configurations and conformations established by X-ray and NMR analysis. Only 5β-ambrox (=1,2,3a,4,5,5aβ,6,7,8,9,9a,9bα-dodecahydro-3aβ,6,6,9aβ-tetramethylnaphtho [2,1-b] furan; 5) has an odor quality comparable to Ambrox ® . The 1,3-synperiplanar/diaxial conformation of the substituents at C(8) (=C(3a)) and C(10) (=C(9a)) has thus been confirmed to be a compulsory structure element for the particular odor