hydrogenchloride; 3 A molecular sieve; sodium cyanoborohydride in methanol 112 h; Ambient temperature; Yield given;

1: NaCNBH3, 1 M HCl, 3-Angstroem molecular sieves / methanol / 112 h / Ambient temperature 2: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature View Scheme

1: NaCNBH3, 1 M HCl, 3-Angstroem molecular sieves / methanol / 112 h / Ambient temperature 2: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature 3: 48 percent / 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 64 h / Ambient temperature 4: H2 / 10percent Pd/C / ethanol / 16 h 5: 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 16 h / Ambient temperature View Scheme

1: NaCNBH3, 1 M HCl, 3-Angstroem molecular sieves / methanol / 112 h / Ambient temperature 2: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature 3: 48 percent / 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 64 h / Ambient temperature View Scheme

<b>Multi-step reaction with 5 steps<br /> </b>1: 19 percent / pyridine, 4-(dimethylamino)pyridine / 16 h / Ambient temperature<br />2: 13 percent / 1 M NaOH / ethanol / 0.25 h / Ambient temperature<br />3: 96 percent / acetonitrile / 20 h / Heating<br />4: NaBH₄ / methanol / 1 h / -10 &deg;C<br />5: HgCl₂ / acetonitrile; H₂O / 0.25 h<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1: 96 percent / acetonitrile / 20 h / Heating<br />2: NaBH₄ / methanol / 1 h / -10 &deg;C<br />3: HgCl₂ / acetonitrile; H₂O / 0.25 h<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 13 percent / 1 M NaOH / ethanol / 0.25 h / Ambient temperature<br />2: 96 percent / acetonitrile / 20 h / Heating<br />3: NaBH₄ / methanol / 1 h / -10 &deg;C<br />4: HgCl₂ / acetonitrile; H₂O / 0.25 h<br /> <br /> &nbsp;

<b>Multi-step reaction with 6 steps<br /> </b>1: 2.) Bu₄NF / 1.) THF<br />2: 19 percent / pyridine, 4-(dimethylamino)pyridine / 16 h / Ambient temperature<br />3: 13 percent / 1 M NaOH / ethanol / 0.25 h / Ambient temperature<br />4: 96 percent / acetonitrile / 20 h / Heating<br />5: NaBH₄ / methanol / 1 h / -10 &deg;C<br />6: HgCl₂ / acetonitrile; H₂O / 0.25 h<br /> <br /> &nbsp;