1: C33H42O3Si3 With n-butyllithium in diethyl ether T=0 - 20°C; 2: trifluoroacetic anhydride in diethyl ether T=0 - 20°C;

1.1: 55 percent / Tf2O / toluene / Heating 2.1: 67 percent / HBr / acetic acid / 75 °C 3.1: HMDS / 70 °C 3.2: Na / toluene / Heating 4.1: n-BuLi / diethyl ether / 0 - 20 °C 4.2: diethyl ether / 0 - 20 °C View Scheme

1.1: 67 percent / HBr / acetic acid / 75 °C 2.1: HMDS / 70 °C 2.2: Na / toluene / Heating 3.1: n-BuLi / diethyl ether / 0 - 20 °C 3.2: diethyl ether / 0 - 20 °C View Scheme

1.1: HMDS / 70 °C 1.2: Na / toluene / Heating 2.1: n-BuLi / diethyl ether / 0 - 20 °C 2.2: diethyl ether / 0 - 20 °C View Scheme