potassium carbonate in methanol 1.) 0 deg C, 5 h, 2.) room temperature, 12 h;

<b>Multi-step reaction with 3 steps<br /> </b>1.1: toluene-4-sulfonic acid / dichloromethane / 12 h / 0 &deg;C / |Inert atmosphere<br />2.1: sodium iodide / acetone / 16 h / |Reflux<br />3.1: n-butyllithium / tetrahydrofuran; hexane / 2 h / -78 &deg;C<br />3.2: 16 h / -78 - 20 &deg;C<br /> <br /> &nbsp;