Dynamic Kinetic Resolution of Racemic γ-Aryl-δ-oxoesters. Enantioselective Synthesis of 3-Arylpiperidines

Cyclodehydration of racemic γ-aryl-δ-oxoesters with (R)- or (S)-phenylglycinol stereoselectively affords bicyclic δ-lactams, in a process that involves a dynamic kinetic resolution. Subsequent reduction of these lactams leads to enantiopure 3-arylpiperidines. Starting from racemic aldehyde esters, this short sequence has been applied to the synthesis of (R)-3-phenylpiperidine and the antipsychotic drug (−)-3-PPP (an (S)-3-arylpiperidine), whereas starting from racemic ketone esters enantiopure cis-2-alkyl-3-arylpiperidines are prepared.