1: 4-methylene-oxetan-2-one With 4-(N,N-dimethlyamino)pyridine; polystyrene Wang resin in 1,4-dioxane T=20°C; 18 h; 2: 3,4-(difluoro)benzaldehyde; urea With hydrogenchloride in 1,4-dioxane T=70°C; Biginelli reaction; 18 h; 3: With trifluoroacetic acid in dichloromethane T=20°C; 0.5 h;

Multistep reaction;