New method of preparing unsaturated fatty hydroxy acids

The present invention relates to a process for preparing a compound of formula (I): wherein a and b represent integers greater than or equal to 0 and R 1, R2 and R8 represent in particular H, said preparation process comprising a step of protection of the alcohol function of the compound of formula (II-a) wherein a, b and R2 are as defined above in formula (I) and R6 and R7 represent in particular a hydrogen atom, this step being followed by oxidative cleavage step of the double bond and a step of implementation of the Wittig-Horner.