1: With copper diacetate; potassium ethylxanthate in N,N-dimethyl-formamide T=80°C; Ullmann type reaction; 15 h; Inert atmosphere; 2: With hydrogenchloride in water; N,N-dimethyl-formamide T=20°C; 8 h; Inert atmosphere;

potassium carbonate; dimethyl sulfoxide T=140°C; Air atmosphere;