1: 1.) CoCl2*6H2O, semicorrin, NaBH4, 2.) pTsOH / 1.) DMF, ethanol, 40 deg C, 62 h, 2.) ethanol, water, 20 deg C, 24 h 2: triphenylphosphine dibromide / CH2Cl2 / 6 h / 20 °C 3: 18-crown-6 / acetonitrile / 22 h / 40 °C View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1: 59 percent / imidazole / dimethylformamide / 17 h / 20 &deg;C<br />2: 77 percent / diisopropylethylamine / CH₂Cl₂ / 60 h / Heating<br />3: 56 percent / NaH / tetrahydrofuran / -70 deg C, then reflux, 1 h<br /> <br /> &nbsp;