Patent ID: 6939845

Claim:
A fragrance precursor of formula I: wherein the dotted lines indicating one or two optional double bonds in the cyclic acetal, that forms a fragrant ketone of formula II: and a fragrant lactone of formula III: containing not more than 20 carbon atoms, wherein R 1 to R 5 represent independently H, —NO 2 , linear or branched C 1 -C 6 -alkyl, C 2 -C 6 -alkenyl, C 2 -C 6 -alkynyl, or C 1 -C 4 -alkoxy, R 1 and R 2 , R 2 and R 3 , R 3 and R 4 , and R 4 and R 5 may form together one or two aliphatic or aromatic rings, these rings may optionally contain linear or branched C 1 -C 4 -alkyl, C 2 -C 4 -alkenyl, or C 2 -C 4 -alkynyl residues, and these rings and residues may comprise one or more oxygen atoms, R 6 and R 7 are independently H, linear or branched C 1 -C 6 -alkyl-, C 2 -C 6 -alkenyl, or C 2 -C 6 -alkynyl, and R 6 or R 7 may form with either R 1 or R 5 a carbocyclic ring optionally substituted by an aliphatic residue, n is either 0 or 1, R 8 to R 15 are independently H, branched or linear C 1 -C 15 -alkyl, C 2 -C 15 -alkenyl, C 2 -C 15 -alkynyl, or C 1 -C 4 -alkoxy, they may form together one or more aliphatic or aromatic rings, these rings may optionally contain branched or linear C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl, or C 2 -C 10 -alkynyl residues, and these rings and residues may comprise one or more oxygen atoms, or R 8 and R 9 together; R 10 and R 11 together; R 12 and R 13 together; or R 14 and R 15 together represent H, branched or linear C 2 -C 15 -alkyl, C 2 -C 15 -alkenyl, C 2 -C 15 -alkynyl or C 1 -C 4 -alkoxy when the ring carbon atom supporting these groups is unsaturated and with the proviso that fragrance precursors of formula (I) wherein (1) the ring of the acetal is saturated, and n is 1, and all of R 8 to R 15 are H, or (2) the ring of the acetal is saturated, and n is 1, and all of R 10 to R 15 are H and either R 8 is C 6 and R 9 is H or R 9 is C 6 and R 8 is H are excluded.