1: 3-ethyl-4-oxo-2-thioxo-thiazolidine; ethyl isothiocyanatoacetate With 1,8-diazabicyclo[5.4.0]undec-7-ene in N,N-dimethyl-formamide 2 h; Cooling with ice; 2: ethyl bromoacetate in N,N-dimethyl-formamide T=80°C; 4 h;

hydrogenchloride; water; acetic acid T=90°C; 4 h;