Synthesis and characterization of four diastereomers of -lactamase inhibitor drug intermediate

A short and efficient stereo-retentive synthesis of three stereoisomers (two diastereomer and one enantiomer) of oxalate salt of benzyl (2S,5R)-5-(benzyloxyamino)piperidine-2-carboxylate (8) has been described. Compound 8 is a key raw material for the synthesis of beta-lactamase inhibitors, was synthesized in high diastereomeric excess through the diastereomeric resolution of L-pyroglutamic acid without the need for a chiral resolving agent. In this report, we describe synthesis process and the information of a chiral high performance liquid chromatography (CHPLC) method to identify these isomers. The efficient control process to control these isomers is also described. The developed CHPLC method was validated for the accurate determination of the diastereomeric purity of compound 8.{Graphical Abstract}