1: 99 percent / conc. H2SO4 / acetonitrile; H2O / 65 °C 2: 81 percent / pyridinium dichromate, 4 Angstroem sieves / CH2Cl2 / Ambient temperature 3: 1.) DBU, 2.) AcOH-THF / 1.) CH2Cl2, -78 deg C, 2.) -78 deg C to r.t. View Scheme

<b>Multi-step reaction with 4 steps<br /> </b>1: 1.) LDA / 1.) THF, -78 deg C, 2.) up to r.t.<br />2: 1.) Li-deriv. / 1.) THF, -78 deg C, 2.) THF<br />3: 99 percent / potassium t-butoxide, t-BuOH / tetrahydrofuran / Ambient temperature<br />4: 1.) n-BuLi / 1.) THF, -78 deg C, 5 min., 2.) a) THF, -78 deg C, 5 min., b) AcOH-THF, -78 deg C -&gt; r.t.<br /> <br /> &nbsp;