1: 90 percent / thiourea / methanol / 2 h / Heating 2: 80 percent / 4A molecular sieves, N-iodosuccinimide, silver triflate / CH2Cl2; toluene / 0.17 h / 0 °C 3: 83 percent / NaOMe, MeOH / CH2Cl2 / 5 h / Ambient temperature View Scheme

<b>Multi-step reaction with 2 steps<br /> </b>1: 1.) dibutyltin oxide / 1.) MeOH, reflux, 2 h, 2.) CH₂Cl₂, 0 deg C, 30 min<br />2: 91 percent / pyridine / CH₂Cl₂ / 5 h / 0 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 4 steps<br /> </b>1: 65 percent / K₂CO₃ / acetone / Ambient temperature<br />2: 92 percent / NaOMe, MeOH / 5 h / Ambient temperature<br />3: 1.) dibutyltin oxide / 1.) MeOH, reflux, 2 h, 2.) CH₂Cl₂, 0 deg C, 30 min<br />4: 91 percent / pyridine / CH₂Cl₂ / 5 h / 0 &deg;C<br /> <br /> &nbsp;