potassium carbonate in N,N-dimethyl-formamide T=80°C; 18 h; Inert atmosphere;

potassium hydroxide in ethanol T=78°C; 1.5 h;

N-bromosuccinmide in tetrachloromethane

1.1: n-butyllithium / tetrahydrofuran; hexane / 1 h / -90 °C 1.2: trimethylborate / tetrahydrofuran; hexane / 0.5 h / -70 °C 1.3: 51 percent / aq. ammonium chloride / tetrahydrofuran; hexane / 1 h / 20 °C 2.1: 85 percent / molecular sieves 4 Angstroem / tetrahydrofuran / 2 h / 20 °C View Scheme

1: With n-butyllithium in tetrahydrofuran; hexane T=-90°C; 1 h; 2: With boric acid trimethyl ester in tetrahydrofuran; hexane T=-70°C; 0.5 h; 3: With ammonium chloride in tetrahydrofuran; hexane T=20°C; 1 h;