1: (1,1-dimethylethyl)dimethyl(4-pentynyloxy)-silane With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: N,N-dimethyl-formamide in tetrahydrofuran; hexane T=-78 - 0°C; 1.25 h;

manganese(IV) oxide in dichloromethane Ambient temperature;

1: 92 percent / Et3N, 4-(dimethylamino)pyridine / CH2Cl2 / 6 h / Ambient temperature 2: 1.) n-BuLi / 1.) THF, hexane, -78 deg C, 1 h, 2.) THF, hexane, from -78 deg C to RT, overnight 3: 91 percent / MnO2 / CH2Cl2 / Ambient temperature View Scheme

1: 92 percent / Et3N, 4-(dimethylamino)pyridine / CH2Cl2 / 6 h / Ambient temperature 2: 1.) n-BuLi / 1.) THF, hexane, -78 deg C, 1 h, 2.) THF, hexane, from -78 deg C to RT, overnight 3: 91 percent / MnO2 / CH2Cl2 / Ambient temperature View Scheme

1: 1.) n-BuLi / 1.) THF, hexane, -78 deg C, 1 h, 2.) THF, hexane, from -78 deg C to RT, overnight 2: 91 percent / MnO2 / CH2Cl2 / Ambient temperature View Scheme

Multistep reaction;

Multistep reaction;