1: acetic acid With chloroformic acid ethyl ester; triethylamine in dichloromethane T=0°C; 1 h; 2: piperidine-4-methanol in dichloromethane T=0 - 20°C; 5 h;

acetic anhydride in ethanol

triethylamine in dichloromethane T=0 - 20°C; 18 h; chemoselective reaction;