Process for the preparation of (3E, 7E)-homofarnesol

A process for preparing compounds of formula I

• in which
• R1 is a straight-chain or branched, optionally mono- or polyunsaturated hydrocarbyl radical, and R2 is H or C1-C6-alkyl, where
• a) a carbonyl compound of formula II
• in which R1 and R2 have the meanings above, is reacted by means of Wittig olefination to give a cyclopropane of formula (III)
• b) the cyclopropane of the formula III is reacted, with ring opening, to give a compound of formula IV
• in which X is halogen or O—R′, in which R′ is H, acyl, Tf-acetyl or SO2—R″, and R″ is alkyl or aryl;
• and
• c) the compound of the formula IV is converted to the formula I compound.