1.1: 1 h / Reflux 2.1: N-ethyl-N,N-diisopropylamine / N,N-dimethyl-formamide / 1.5 h / 50 °C 3.1: water; lithium hydroxide hydrate / tetrahydrofuran; methanol / 3 h / 18 - 25 °C 3.2: 0 °C 4.1: N-ethyl-N,N-diisopropylamine; HATU / isobutyramide / 1 h / 18 - 25 °C View Scheme

1.1: 1 h / Reflux 2.1: N-ethyl-N,N-diisopropylamine / N,N-dimethyl-formamide / 1.5 h / 50 °C 3.1: water; lithium hydroxide hydrate / tetrahydrofuran; methanol / 3 h / 18 - 25 °C 3.2: 0 °C 4.1: N-ethyl-N,N-diisopropylamine; HATU / isobutyramide / 1 h / 18 - 25 °C 5.1: borane-THF / tetrahydrofuran / 18 - 25 °C 5.2: 3 h 5.3: pH ~ 10 View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1: toluene-4-sulfonic acid / toluene / 3 h / Dean-Stark conditions; Reflux<br />2: triethylamine / 18 - 25 &deg;C<br />3: tributylphosphine; 1-[[(1-piperidinylcarbonyl)azo]carbonyl]-piperidine / tetrahydrofuran / 2.5 h / Inert atmosphere<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1.1: sodium tetrahydroborate / tetrahydrofuran / 6 h / 0 - 25 &deg;C<br />1.2: 0 &deg;C / pH 4<br />2.1: toluene-4-sulfonic acid / toluene / 3 h / Dean-Stark conditions; Reflux<br />3.1: triethylamine / 18 - 25 &deg;C<br />4.1: tributylphosphine; 1-[[(1-piperidinylcarbonyl)azo]carbonyl]-piperidine / tetrahydrofuran / 2.5 h / Inert atmosphere<br /> <br /> &nbsp;

<b>Multi-step reaction with 2 steps<br /> </b>1: triethylamine / 18 - 25 &deg;C<br />2: tributylphosphine; 1-[[(1-piperidinylcarbonyl)azo]carbonyl]-piperidine / tetrahydrofuran / 2.5 h / Inert atmosphere<br /> <br /> &nbsp;

<b>Multi-step reaction with 5 steps<br /> </b>1.1: acetic anhydride / 18 - 25 &deg;C<br />2.1: sodium tetrahydroborate / tetrahydrofuran / 6 h / 0 - 25 &deg;C<br />2.2: 0 &deg;C / pH 4<br />3.1: toluene-4-sulfonic acid / toluene / 3 h / Dean-Stark conditions; Reflux<br />4.1: triethylamine / 18 - 25 &deg;C<br />5.1: tributylphosphine; 1-[[(1-piperidinylcarbonyl)azo]carbonyl]-piperidine / tetrahydrofuran / 2.5 h / Inert atmosphere<br /> <br /> &nbsp;