1: furan-2-carboxylic acid With thionyl chloride T=100°C; 5 h; 2: With sodium azide; N-hexadecyl-N,N,N-trimethylammonium bromide in dichloromethane T=20°C; 18 h; 3: ethanol T=80°C; 4 h; Further stages.;

12 h; Heating;