1: With lithium chloride in tetrahydrofuran T=-78°C; 0.166667 h; 2: With lithium diisopropyl amide in tetrahydrofuran T=-78°C; 0.666667 h; 3: With N-fluoro-N-(phenylsulfonyl)benzene-sulfonamide in tetrahydrofuran T=-78°C; 0.166667 h;