1.1: diisobutylaluminium hydride / dichloromethane; toluene / 12 h / -78 °C 2.1: n-butyllithium / diethyl ether / 0.5 h / 0 °C / Inert atmosphere 2.2: 2 h / 20 °C 3.1: tetrabutyl ammonium fluoride / tetrahydrofuran / 3 h / 20 °C 4.1: pyridine; 4-(N,N-dimethlyamino)pyridine; acetic anhydride / dichloromethane / 0.33 h / 0 - 20 °C 4.2: 0.25 h / 20 °C View Scheme

<b>Multi-step reaction with 6 steps<br /> </b>1: sodium hydroxide / methanol; water / 2 h / 20 &deg;C<br />2: 4-(N,N-dimethlyamino)pyridine; BOP; triethylamine / N,N-dimethyl-formamide / 3 h / 20 &deg;C<br />3: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 24 h / 0 - 20 &deg;C<br />4: pyridine; phosphorus pentachloride / dichloromethane / 8 h / 0 &deg;C<br />5: dichloromethane / 1 h / -30 - -20 &deg;C<br />6: water / dichloromethane / 12 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / dichloromethane / 24 h / 0 - 20 &deg;C<br />2: pyridine; phosphorus pentachloride / dichloromethane / 8 h / 0 &deg;C<br />3: dichloromethane / 1 h / -30 - -20 &deg;C<br />4: water / dichloromethane / 12 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1: pyridine; phosphorus pentachloride / dichloromethane / 8 h / 0 &deg;C<br />2: dichloromethane / 1 h / -30 - -20 &deg;C<br />3: water / dichloromethane / 12 h / 20 &deg;C<br /> <br /> &nbsp;