1: 1.) trifluoroacetic anhydride, pyridine, 2.) aq. LiOH / 1.) CH2Cl2, 0 deg C, 15 min, 2.) THF, from 0 deg C to RT 2: 90 percent / Hg(OCOCF3)2, BF3*OEt2 View Scheme

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '472690', constants.ctx, '0')">toluene-4-sulfonic acid</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '1730800', constants.ctx, '0')">dichloromethane</a> <br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1.1: NaHMDS / pyridine; tetrahydrofuran / 0.5 h / 0 &deg;C<br />1.2: 84 percent / pyridine; tetrahydrofuran / 0.5 h / 0 &deg;C<br />2.1: 94 percent / PTSA / CH₂Cl₂ / 2 h / 0 - 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: 84 percent / NaHMDS, pyridine / tetrahydrofuran<br />2: 94 percent / TsOH / CH₂Cl₂ <br /> <br /> &nbsp;