1: trimethylsilylpropynoyl chloride With 1-hydroxy-pyrrolidine-2,5-dione; dicyclohexyl-carbodiimide in dichloromethane T=20°C; 2.5 h; 2: ethanolamine in tetrahydrofuran 10 h; Further stages.;

in diethyl ether T=0°C; 1 h;

in benzene T=80°C; 4 h;