1.1: N-ethyl-N,N-diisopropylamine / chloroform / 1 h / 20 °C / Sonographic reaction 1.2: 1 h / 20 °C / Sonographic reaction 2.1: benzotriazol-1-ol / N,N-dimethyl-formamide; chloroform; methanol / 18 h / 20 °C 3.1: trifluoroacetic acid / dichloromethane 4.1: Bovine pancreas trypsin / 24 h / 37 °C / pH 8 / Aqueous Tris buffer; Enzymatic reaction View Scheme

1-amino-pyrrolidine-2,5-dione; hydrochloride in N,N-dimethyl-formamide T=100°C; 18 h;