hydrogen fluoride T=0°C; 2 h;

<b>Multi-step reaction with 2 steps<br /> </b>1: p-toluenesulfonic acid / benzene / 1.5 h / Heating<br />2: 1) 1,2-dibromoethane, Mg; 2) TMEDA / 1) reflux, THF, 15 min; 2) THF, -78 deg C, overnight<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 86 percent / polyphosphoric acid / 0.67 h / 75 &deg;C<br />2: NaBH₄ / ethanol / Ambient temperature<br />3: p-toluenesulfonic acid / benzene / 1.5 h / Heating<br />4: 1) 1,2-dibromoethane, Mg; 2) TMEDA / 1) reflux, THF, 15 min; 2) THF, -78 deg C, overnight<br /> <br /> &nbsp;