Novel Cyclopropyl β-Amino Acid Analogues of Pregabalin and Gabapentin That Target the α<INF>2</INF>-δ Protein

As part of a program aimed at generating compounds with affinity for the α<INF>2</INF>-δ subunit of voltage-gated calcium channels, several novel β-amino acids were prepared using an efficient nitroalkane-mediated cyclopropanation as a key step. Depending on the ester that was chosen, the target amino acids could be prepared in as few as three steps. The cyclopropyl amino acids derived from ketones proved to be potent binders of the α<INF>2</INF>-δ subunit of voltage-gated calcium channels, but did not interact with the large neutral amino acid system L (leucine) transporter. Anticonvulsant effects were observed in vivo with compound <BO>34</BO> but only after intracerebroventricular (icv) administration, presumably due to inadequate brain concentrations of the drug being achieved following oral dosing. However, pregabalin <BO>1</BO> was active in the DBA/2 model after oral (and icv) dosing, supporting a hypothesis that active transport is a prerequisite for such zwitterionic species to cross the blood−brain barrier.