1: 1.) NaCNBH3; 2.) mCPBA / 1.) HOAc; 2.) -78 deg C to r.t., CH2Cl2 2: 79 percent / TFA / CH2Cl2 / 5 h / 0 - 20 °C 3: 81 percent / Et3N, 4-DMAP / CH2Cl2 / 0 °C 4: 73 percent / TFA, 70 percent aq. H2O2 / CH2Cl2 / 0 °C View Scheme

<b>Multi-step reaction with 4 steps<br /> </b>1: 70 percent / NaH / tetrahydrofuran / 0 - 20 &deg;C<br />2: 83 percent / n-BuLi / tetrahydrofuran / -78 - 0 &deg;C<br />3: 90 percent / methanol / 60 &deg;C<br />4: 51 percent / LDA / tetrahydrofuran / -78 - 0 &deg;C<br /> <br /> &nbsp;