1: 2-(2-propynyloxy)-tetrahydro-2H-pyran With n-butyllithium; toluene-4-sulfonic acid in tetrahydrofuran; hexane T=-78 - 0°C; 0.333333 h; 2: tert-butylchlorodiphenylsilane in tetrahydrofuran; hexane T=0 - 20°C; 3: With toluene-4-sulfonic acid in methanol 3 h; Further stages.;

1.1: n-BuLi / tetrahydrofuran; hexane / 0.58 h / -80 °C 1.2: tetrahydrofuran; hexane / 0.17 h / -80 - 20 °C 2.1: p-toluenesulfonic acid monohydrate / acetone; H2O / 0.67 h / Heating View Scheme

n-butyllithium 1.) hexane, THF, -78 deg C, 2 h, 2.) hexane, THF, RT, 2 h; Yield given. Multistep reaction;

1.1: MeMgCl / tetrahydrofuran / 0.67 h / 0 °C 1.2: tetrahydrofuran / -78 - 20 °C 2.1: CuBr; LiBr / tetrahydrofuran / 0.5 h / 0 °C 2.2: 96 percent / tetrahydrofuran / 2 h / 20 °C View Scheme