Inversion of configuration of (S)-beta-hydroxy-gamma-butyrolactone with total retention of the enantiomeric purity

In this paper we report the inversion of configuration of (S)-beta-hydroxy- gamma-butyrolactone [(S)-1] to its (R) enantiomer (R)-1, with total retenti on of the enantiomeric purity, by a four-step procedure. The (R)-beta-hydro xy-gamma-butyrolactone [(R)-1] was thus synthetized with an overall chemica l yield of 47% and > 97% ee, This transformation opens an economic route to the production of (R)-GABOB and (R)-carnitine, among other biologically ac tive compounds, from a D-hexose source, or, alternatively, from the industr ial waste compound (S)-carnitine. During the reaction sequence, the interme diate beta-lactone 4 is also prepared, which is now under investigation as a chiral synthon for new synthetic applications.