Esters of allyl substituted by a difluoromethylene group, method for the synthesis thereof and use thereof

A compound of formula (I):

• wherein:
• Rf is a radical carrying a perfluoromethylene group, which group provides the link with the remainder of the molecule;
• R1 and R3, which are the same or different, represent hydrogen, alkyl or aryl radicals;
• and
• Ψ is an electron-withdrawing group such that Ψ-O—H is an acid with a pKa value in water of at most 8, optionally of at most 5.

A process for the synthesis of a compound of formula (I) of the formula:

• wherein:
• Rf is a radical carrying a perfluoromethylene group, which group provides the link with the remainder of the molecule;
• R1 and R3, which are the same or different, represent hydrogen, alkyl or aryl radicals;
• and
• Ψ is an electron-withdrawing group such that Ψ-O—H is an acid with a pKa value in water of at most 8, optionally of at most 5 said process comprising the steps of:
• a) reacting a compound of formula (III):
• where Ξ is a leaving group chosen from pseudohalogens and halogens, with a strong nitrogenous base, the associated acid of which exhibits a pKa value of at least 12, and/or an anionic base, with the proviso that, when the base is a nonnitrogenous anionic base, the latter is in the presence of a polar solvent or a mixture of polar solvents.