1: 69 percent 2: 78 percent / 10percent HBF4 / tetrahydrofuran / Ambient temperature 3: 70 percent / 10percent HBF4, HgO / tetrahydrofuran / Ambient temperature 5: tetrahydrofuran / -78 °C View Scheme

1: 98 percent / NaBH4 / methanol / 3 h / Ambient temperature 2: 75 percent / aq. 48percent HBF4, red HgO / tetrahydrofuran / 48 h View Scheme

1: NaBH4 / methanol / 0.5 h / Ambient temperature 2: 1) BF3*Et2O / 1) room temp., 5 min, 2) reflux, 15 h View Scheme

1: 69 percent / tetrahydrofuran / 1.5 h / -78 - -10 °C 2: 51 percent / aq. 48percent HBF4, red HgO / tetrahydrofuran / 24 h View Scheme

sodium tetrahydroborate

in tetrahydrofuran T=-78 - -10°C; 1.5 h;

copper(l) iodide; n-butyllithium; thiophenol 1.) THF. 0 deg, 10 min, 2.) 0 deg C, 15 min, 3.) -78 deg C, 1 h, 4.) THF, -60 deg C, 40 min, RT.;

1: 1.) sec-BuLi, Tetramethylethylenediamine / 1.) THF, a) 1h, -78 deg C, b) 1 h 40 deg C, 2.) THF, a) 0.5 h, -78 degC, b) 2 h to 0 deg C 2: 66 percent / 10percent HBF4 / tetrahydrofuran / Ambient temperature 3: 9 percent / Dimethyl(methylthio)sulfonium fluoroborate / acetonitrile / 20 h / Ambient temperature View Scheme