Synthesis of (±)-Pregabalin by Utilizing a Three-Step Sequential-Flow System with Heterogeneous Catalysts

Abstract

(±)-Pregabalin, a γ-amino acid derivative, has been synthesized by utilizing flow methods. A three-step sequential-flow reaction starting from commercial isovaleraldehyde and methyl malonate proceeded smoothly with heterogeneous catalysts to afford the precursor of pregabalin in yields of 75–100 %, and a space-time yield of 52.2 g/L d was reached. In addition, a heterogeneous catalyst for the Knoevenagel reactions of aldehydes with malonates, which is the first step of the synthesis, has been developed. Pregabalin was finally obtained by acid-catalyzed hydrolysis of the precursor followed by neutralization.