Process for the preparation of omega-benzyl esters of amino diacids and of alkanesulphonates of these esters, and these alkanesulphonates

The invention relates to a process for the preparation of an omega-benzyl ester of an amino diacid, characterized in that the amino diacid is reacted with a benzyl alcohol derivative of formula (I) in which the R substituent or substituents, which are identical or different, represent a hydrogen atom, a C1 to C4 alkyl group, a C1 to C4 alkoxy group or a halogen atom and n is equal to 1, 2 or 3, in the presence of at least one mol per mole of the amino diacid of an alkanesulphonic acid, optionally in the presence of a solvent. The intermediate alkanesulphonates of the omega-benzyl esters of amino diacids and the omega-benzyl esters of amino diacids are obtained with a good yield and an excellent purity by virtue of this process.