1: di-isopropyl azodicarboxylate; triphenylphosphine / toluene / 1.5 h 2: water; 2,3-dicyano-5,6-dichloro-p-benzoquinone / dichloromethane / 1 h / 20 °C 3: Grubb's 2nd generation catalyst / dichloromethane / 6 h / 40 °C 4: hydrogenchloride; water / tetrahydrofuran / 20 h View Scheme

<b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '3570522', constants.ctx, '0')">tetrabutyl ammonium fluoride</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '102391', constants.ctx, '0')">tetrahydrofuran</a> <br />T=20&deg;C;&nbsp;24&nbsp;h;&nbsp;<br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 2 h / 20 &deg;C<br />2.1: sodium hydrogencarbonate; Dess-Martin periodane / dichloromethane / 1 h<br />3.1: potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / Cooling<br />3.2: 2 h / 20 &deg;C / Cooling<br />4.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 24 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1.1: sodium hydrogencarbonate; Dess-Martin periodane / dichloromethane / 1 h<br />2.1: potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / Cooling<br />2.2: 2 h / 20 &deg;C / Cooling<br />3.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 24 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1.1: 18-crown-6 ether; potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / Cooling<br />1.2: 2 h / 20 &deg;C / Cooling<br />2.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 24 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 7 steps<br /> </b>1.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 1 h / -78 &deg;C<br />1.2: -78 - 20 &deg;C<br />2.1: titanium(IV) isopropylate; (S)-(minus;)-1,1'-bi-2-naphthol / toluene / 72 h / -78 - -15 &deg;C / Molecular sieve; Inert atmosphere<br />3.1: sodium hydride / tetrahydrofuran; mineral oil / 1 h / 0 &deg;C<br />3.2: 2 h / 20 &deg;C<br />4.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 2 h / 20 &deg;C<br />5.1: sodium hydrogencarbonate; Dess-Martin periodane / dichloromethane / 1 h<br />6.1: potassium hexamethylsilazane / tetrahydrofuran; toluene / 0.5 h / Cooling<br />6.2: 2 h / 20 &deg;C / Cooling<br />7.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 24 h / 20 &deg;C<br /> <br /> &nbsp;