Résumé
When synthesizing arylpiperazine library modified with N-acylated amino acid derivatives (e. g., cyclized aspartic acid, cyclized glutamic acid, proline) we wished to rapidly determine the way of cyclization of N-acylated glutamic acid derivatives. During concomitant cleavage and cyclization two alternative routes were possible-either formation of six-member imide (glutarimide) or five-member lactam. Application of MS/MS and (1)H NMR method allowed us to establish that cyclization of N-acylated glutamic acid derivatives preceded to lactams-N-acylated pyroglutamic acid derivatives.