1: isonicotinic acid; 2,2-dimethyl-1,3-dioxolane-4,5-dione With 4-(N,N-dimethlyamino)pyridine; dicyclohexyl-carbodiimide in dichloromethane T=0 - 20°C; 2 h; 2: ethanol With toluene-4-sulfonic acid 1 h; Heating / reflux;