1: Boc2O; Et3N / 20 °C 2: DMAP / toluene / 90 - 95 °C View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1.1: DIBAL-H / toluene / 2 h / -78 &deg;C<br />1.2: 90.7 percent / 6 h / Heating<br />2.1: 1M HCl / methanol / 2 h / 20 &deg;C<br />3.1: LiOH / tetrahydrofuran; H₂O / 8 h / 20 &deg;C<br /> <br /> &nbsp;