Lactones 31. Synthetic odoriferous unsaturated γ‐lactones

Starting from γ, δ-unsaturated terpenoid acids, the corresponding δ-iodo-γ-lactones and γ-iodo-δ-lactones were obtained. Dehydrohalogenation of δ-iodo-γ-lactones with DBU gave unsaturated γ-lactones with an exocyclic or alkyl chain double bond. Both types of double bonds possessed the E configuration. The composition of product mixture of dehydrohalogenation strongly depended on the conditions (solvent, temperature) of the process. Odour evaluation of the lactones obtained showed that lactones with two double bonds in the molecule ( 11 and 12) possess intensive, well-marked, fresh mushroom odours. Lactones with one double bond and one methyl group at C-4 ( 5a, 6a, 6b and 5d, 6d, 6e) are characterized, in general, by milky, coconut and creamy odours with different notes. Lactones with two methyl groups at C-4 possess herbal ( 5c, 5f) or woody ( 6c) odours. Copyright © 2008 John Wiley & Sons, Ltd.