1: 100 percent / Bu4NF / tetrahydrofuran / 1 h / 20 °C 2: 92 percent / 4-(dimethylamino)pyridine; camphorsulfonic acid; dicyclohexylcarbodiimide / CH2Cl2 / 18.5 h / 20 °C 3: 83 percent / CF3CO2H / tetrahydrofuran; H2O / 22 h / 20 °C 4: 96 percent / 4-(dimethylamino)pyridine; camphorsulfonic acid; dicyclohexylcarbodiimide / CH2Cl2 / 14 h / 20 °C 5: 19 percent / CH3CO2H / propan-2-ol; H2O 6: triethylamine / toluene / 1 h / 20 °C 7: triethylamine; 4-(dimethylamino)pyridine / toluene / 3.5 h / 80 °C 8: 90 percent / trifluoroacetic acid / CH2Cl2 / 7.5 h / 20 °C View Scheme

<b>Multi-step reaction with 5 steps<br /> </b>1: Corey-AD-ligand-α non MeI salt; methanesulfonamide; K₃[Fe(CN)6] / K₂OsO₄*2H₂O; K₂CO₃ / 2-methyl-propan-2-ol; H₂O / 18.5 h / 0 &deg;C<br />2: 78 percent / 4-(dimethylamino)pyridine; triethylamine / CH₂Cl₂ / 12.25 h / 0 - 20 &deg;C<br />3: triphenylphosphine; diethyl azodicarboxylate / benzene / 4.25 h / 20 &deg;C<br />4: 697 mg / NH₄OH / methanol; H₂O / 1.5 h / 20 &deg;C<br />5: 87 percent / N-ethyldiisopropylamine / CH₂Cl₂ / 66 h / 20 &deg;C<br /> <br /> &nbsp;

Stage #1: <a href="#" onclick="return RXDsubstances(event, this, '8151221', constants.ctx, '0')">(4R,5S)-(E)-5-(t-butyl(dimethyl)silyloxy)-4-hydroxy-2-hexenoic acid tert-butyl ester</a> <b>With</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '605301', constants.ctx, '0')">N-ethyl-N,N-diisopropylamine</a>&nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '605264', constants.ctx, '0')">1,2-dichloro-ethane</a> <br />T=20&deg;C;&nbsp;0.5&nbsp;h;&nbsp;<br />Stage #2: <a href="#" onclick="return RXDsubstances(event, this, '1900576', constants.ctx, '0')">1-(chloromethoxy)-2-methoxyethane</a> &nbsp;<b>in</b>&nbsp; <a href="#" onclick="return RXDsubstances(event, this, '605264', constants.ctx, '0')">1,2-dichloro-ethane</a> <br />60&nbsp;h;&nbsp;&nbsp;Heating;&nbsp;<br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 78 percent / 4-(dimethylamino)pyridine; triethylamine / CH₂Cl₂ / 12.25 h / 0 - 20 &deg;C<br />2: triphenylphosphine; diethyl azodicarboxylate / benzene / 4.25 h / 20 &deg;C<br />3: 697 mg / NH₄OH / methanol; H₂O / 1.5 h / 20 &deg;C<br />4: 87 percent / N-ethyldiisopropylamine / CH₂Cl₂ / 66 h / 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1.1: LDA; HMPA / tetrahydrofuran / 0.75 h / -78 &deg;C<br />1.2: 65 percent / tetrahydrofuran / 2 h<br />2.1: 75 percent / lithium aluminum hydride / tetrahydrofuran / 0 - 20 &deg;C<br />3.1: DIPEA / 1,2-dichloro-ethane / 0.5 h / 20 &deg;C<br />3.2: 95 percent / 1,2-dichloro-ethane / 60 h / Heating<br /> <br /> &nbsp;