Process for substituted 3-hydroxybutyrate esters

A process for the preparation of a compound of formula (I)

• from a compound of formula (II)
• without a reaction solvent being present which comprises the steps of
• (i) reacting the compound of formula (II) with hydrogen in the presence of a catalytic amount of platinum and a catalytic amount of an acid or a base to form the compound of formula (I), and
• (ii) separating the compound of formula (I) from the platinum catalyst,
• wherein
• X is fluoro or chloro,
• R is alkyl, haloalkyl, polyhaloalkyl, alkyl substituted with NR2R3, hydroxy or OR4, phenyl or phenyl substituted with one or more groups independently selected from halo, alkyl, hydroxy, alkoxy, haloalkoxy, polyhaloalkoxy, haloalkyl or polyhaloalkyl,
• R′ is a hydrogen atom, alkyl, haloalkyl, polyhaloalkyl, alkyl substituted with NR2R3, hydroxy or OR4, phenyl or phenyl substituted with one or more groups independently selected from halo, alkyl, hydroxy, alkoxy, haloalkoxy, polyhaloalkoxy, haloalkyl or polyhaloalkyl,
• R2 and R3 are each independently a hydrogen atom, alkyl, or together with the nitrogen atom to which they are attached form a 5- or 6-membered heterocyclic ring, and
• R4 is alkyl, haloalkyl or polyhaloalkyl.