toluene-4-sulfonic acid in 1,2-dichloro-ethane T=80°C; 1 h;

<b>Multi-step reaction with 2 steps<br /> </b>1.1: tetrahydrofuran / 1 - 10 h / 20 &deg;C<br />2.1: lithium diisopropyl amide / tetrahydrofuran; hexane / 1 h / -78 &deg;C<br />2.2: 1 h / -78 &deg;C<br /> <br /> &nbsp;