Beta-analogs of PLG (L-prolyl-L-leucyl-glycinamide): ex-chiral pool syntheses and dopamine D2 receptor modulating effects.

Starting from (S)- and (R)-aspartic acid enantiomerically pure beta-proline derivatives were synthesized. These chiral building blocks were transformed into beta-analogs of the dopamine receptor modulating peptide PLG. According to dopamine receptor binding studies, significant enhancement of [3H]pramipexole binding was observed for the isomeres 1a,b and 2a-c. The derivative 1b revealed an activity comparable to PLG.