1: copper(I) bromide dimethylsulfide complex / tetrahydrofuran; toluene / 1 h / -10 °C / Inert atmosphere 2: toluene-4-sulfonic acid / methanol; water / 6 h / 50 °C 3: 2-picoline / ethyl acetate / 12 h / 0 - 5 °C 4: triethylamine / ethyl acetate / 2 h 5: potassium hydroxide / methanol; dichloromethane / 2 h / 0 - 20 °C View Scheme

1: copper(I) bromide dimethylsulfide complex / tetrahydrofuran; toluene / 1 h / -10 °C / Inert atmosphere 2: toluene-4-sulfonic acid / methanol; water / 6 h / 50 °C 3: 2-picoline / ethyl acetate / 12 h / 0 - 5 °C 4: triethylamine / ethyl acetate / 2 h 5: potassium hydroxide / methanol; dichloromethane / 2 h / 0 - 20 °C View Scheme

<b>Multi-step reaction with 6 steps<br /> </b>1: sodium tetrahydroborate; calcium chloride / ethanol / 3 h / -5 - 5 &deg;C<br />2: potassium hydroxide / ethanol / 3 h / 10 &deg;C<br />3: formic acid methyl ester / 0.5 h<br />4: sodium azide / water / 6 h / 60 &deg;C<br />5: triphenylphosphine / acetonitrile / 16 h / 40 &deg;C / Reflux<br />6: sodium hydrogencarbonate / 1,4-dioxane; water / 1 h / 0 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: formic acid methyl ester / 0.5 h<br />2: sodium azide / water / 6 h / 60 &deg;C<br />3: triphenylphosphine / acetonitrile / 16 h / 40 &deg;C / Reflux<br />4: sodium hydrogencarbonate / 1,4-dioxane; water / 1 h / 0 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 7 steps<br /> </b>1: pyridine / dichloromethane / 3 h / 5 &deg;C<br />2: sodium tetrahydroborate; calcium chloride / ethanol / 3 h / -5 - 5 &deg;C<br />3: potassium hydroxide / ethanol / 3 h / 10 &deg;C<br />4: formic acid methyl ester / 0.5 h<br />5: sodium azide / water / 6 h / 60 &deg;C<br />6: triphenylphosphine / acetonitrile / 16 h / 40 &deg;C / Reflux<br />7: sodium hydrogencarbonate / 1,4-dioxane; water / 1 h / 0 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 8 steps<br /> </b>1.1: dihydrogen peroxide / 3 h / 20 &deg;C<br />1.2: 0.5 h<br />1.3: 5 h / 50 &deg;C<br />2.1: pyridine / dichloromethane / 3 h / 5 &deg;C<br />3.1: sodium tetrahydroborate; calcium chloride / ethanol / 3 h / -5 - 5 &deg;C<br />4.1: potassium hydroxide / ethanol / 3 h / 10 &deg;C<br />5.1: formic acid methyl ester / 0.5 h<br />6.1: sodium azide / water / 6 h / 60 &deg;C<br />7.1: triphenylphosphine / acetonitrile / 16 h / 40 &deg;C / Reflux<br />8.1: sodium hydrogencarbonate / 1,4-dioxane; water / 1 h / 0 &deg;C<br /> <br /> &nbsp;