1: 3-(N,N-dimethylamino)-pyridine With boron trifluoride diethyl etherate in tetrahydrofuran T=0°C; 0.5 h; 2: With lithium diisopropyl amide in tetrahydrofuran; hexane T=-78°C; 0.5 h; 3: N,N-dimethyl-formamide in tetrahydrofuran; hexane T=-78 - 20°C; 13 h;