1: 14 percent / HCl / ethyl acetate / 12.5 h / 20 °C 2: SOCl2; DMF / tetrahydrofuran / 20 °C 3: Et3N / tetrahydrofuran; dimethylformamide / 20 °C 4: 50 percent / aq. K2CO3; Pd(PPh3)4 / toluene; ethanol / Heating View Scheme

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '3556712', constants.ctx, '0')">potassium <i>tert</i>-butylate</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '635760', constants.ctx, '0')">toluene</a>;&nbsp;<a href="#" onclick="return RXDsubstances(event, this, '906698', constants.ctx, '0')"><i>tert</i>-butyl alcohol</a> <br />T=90&deg;C;&nbsp;Claisen-Schmidt cyclization;&nbsp;<br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: di-tert-butyl dicarbonate; 4-(N,N-dimethylamino)pyridine / 20 &deg;C<br />2: H₂; aq. HCl / Pd/C / methanol / 20 &deg;C<br />3: 52 percent / K₂CO₃ / dimethylformamide / 70 - 80 &deg;C<br />4: 60 percent / potassium tert-butoxide / toluene; 2-methyl-propan-2-ol / 90 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1: H₂; aq. HCl / Pd/C / methanol / 20 &deg;C<br />2: 52 percent / K₂CO₃ / dimethylformamide / 70 - 80 &deg;C<br />3: 60 percent / potassium tert-butoxide / toluene; 2-methyl-propan-2-ol / 90 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: potassium carbonate / DMF (N,N-dimethyl-formamide) / 94 h / 20 - 80 &deg;C<br />2: sodium t-butanolate / toluene; <i>tert</i>-butyl alcohol / 1 h / 20 - 90 &deg;C / Heating / reflux<br /> <br /> &nbsp;