1,8-diazabicyclo[5.4.0]undec-7-ene in tetrahydrofuran T=20°C; 1 h;

1: 76 percent / NaBH4 / ethanol / 3 h / 20 °C 2: 76 percent / DCC; DMAP / CH2Cl2 3: 94 percent / HMPA; tert-butyldimethylsilyl chloride; LHMDS / tetrahydrofuran / 1.33 h / -78 - 20 °C 4: 90 percent / DBU / tetrahydrofuran / 1 h / 20 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 0.17 h / -78 °C 1.2: tetrahydrofuran; hexane / 0.17 h / -78 °C 2.1: 3.57 g / bromine / CH2Cl2 / 0.17 h / -78 °C 3.1: 76 percent / NaBH4 / ethanol / 3 h / 20 °C 4.1: 76 percent / DCC; DMAP / CH2Cl2 5.1: 94 percent / HMPA; tert-butyldimethylsilyl chloride; LHMDS / tetrahydrofuran / 1.33 h / -78 - 20 °C 6.1: 90 percent / DBU / tetrahydrofuran / 1 h / 20 °C View Scheme

1: 3.57 g / bromine / CH2Cl2 / 0.17 h / -78 °C 2: 76 percent / NaBH4 / ethanol / 3 h / 20 °C 3: 76 percent / DCC; DMAP / CH2Cl2 4: 94 percent / HMPA; tert-butyldimethylsilyl chloride; LHMDS / tetrahydrofuran / 1.33 h / -78 - 20 °C 5: 90 percent / DBU / tetrahydrofuran / 1 h / 20 °C View Scheme

1: 76 percent / DCC; DMAP / CH2Cl2 2: 94 percent / HMPA; tert-butyldimethylsilyl chloride; LHMDS / tetrahydrofuran / 1.33 h / -78 - 20 °C 3: 90 percent / DBU / tetrahydrofuran / 1 h / 20 °C View Scheme

1: 94 percent / HMPA; tert-butyldimethylsilyl chloride; LHMDS / tetrahydrofuran / 1.33 h / -78 - 20 °C 2: 90 percent / DBU / tetrahydrofuran / 1 h / 20 °C View Scheme