1: 2-bromo-3-(trimethylsilyl)norbornadiene With tert.-butyl lithium in tetrahydrofuran T=-78°C; 1 h; 2: chloro-trimethyl-silane in tetrahydrofuran T=-78 - 0°C;

1.1: n-BuLi; t-BuOK / tetrahydrofuran; hexane / 0.5 h / -78 °C 1.2: 1,2-dibromoethane / tetrahydrofuran; hexane / -78 - -40 °C 1.3: 69.8 percent / tetrahydrofuran; hexane / 1 h / 20 °C 2.1: t-BuLi / pentane; diethyl ether / 1 h / -78 °C 2.2: pentane; diethyl ether / 35 h / 20 °C View Scheme