1: 1.) O3, 2.) Me2S / 1.) CH2Cl2, -78 deg C 2: 79 percent / NaH / tetrahydrofuran 3: 1.) HCl, 2.) DBU / 1.) CH2Cl2, MeOH, 2.) toluene, reflux 4: 76 percent / Na(Hg), Na2HPO4 / methanol / 0.17 h / -40 °C View Scheme

<b>Multi-step reaction with 5 steps<br /> </b>1: 92 percent / DIBAL / CH₂Cl₂ / -78 &deg;C<br />2: 87 percent / PPTS / methanol<br />3: 96 percent / Bu₄NF / tetrahydrofuran<br />4: 1.) BuLi / 1.) THF, -78 deg C<br />5: toluene / Irradiation<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 87 percent / PPTS / methanol<br />2: 96 percent / Bu₄NF / tetrahydrofuran<br />3: 1.) BuLi / 1.) THF, -78 deg C<br />4: toluene / Irradiation<br /> <br /> &nbsp;