1: N,N-dimethyl-formamide With phosphorus oxytribromide in chloroform T=0°C; 0.5 h; 2: 3-oxo-2,3-dihydrobenzolt;bgt;selenophene in chloroform T=70°C; Vilsmeier-Haack-Arnold reaction; 6 h;

selenium(IV) oxide; hydrogen bromide in 1,4-dioxane T=15 - 20°C; 70 h;