1: With tert.-butyl lithium in tetrahydrofuran; pentane T=-78°C; 1 h; 2: With boric acid trimethyl ester in tetrahydrofuran; pentane T=-78 - 20°C;

potassium carbonate in N,N-dimethyl-formamide T=90°C;

potassium carbonate in dimethyl sulfoxide T=55°C; 2 h;

1: 91 percent / LDA / heptane; tetrahydrofuran; ethylbenzene / 0.08 h / 0 °C 2: 96 percent / potassium carbonate / dimethylsulfoxide / 2 h / 55 °C View Scheme

1.1: n-butyllithium / diethyl ether; hexane / 1 h / -78 °C 1.2: trimethyl borate / diethyl ether; hexane / -78 - 20 °C 1.3: 91 percent / acetic acid; H2O2 / H2O; diethyl ether; hexane / 16 h / 20 °C 2.1: 96 percent / potassium carbonate / dimethylsulfoxide / 2 h / 55 °C View Scheme

1: 96 percent / N-bromosuccinimide / dimethylformamide / 24 h / 20 °C 2: 91 percent / LDA / heptane; tetrahydrofuran; ethylbenzene / 0.08 h / 0 °C 3: 96 percent / potassium carbonate / dimethylsulfoxide / 2 h / 55 °C View Scheme

1: 96 percent / triethylamine / CH2Cl2 / 0.5 h / 0 °C 2: 96 percent / N-bromosuccinimide / dimethylformamide / 24 h / 20 °C 3: 91 percent / LDA / heptane; tetrahydrofuran; ethylbenzene / 0.08 h / 0 °C 4: 96 percent / potassium carbonate / dimethylsulfoxide / 2 h / 55 °C View Scheme