1: 17 percent / diethyl ether; tetrahydrofuran / 0.5 h / 0 °C 2: 80percent TFA / 24 h / Ambient temperature View Scheme

<b>Multi-step reaction with 2 steps<br /> </b>1: 75 percent / p-TsOH / CH₂Cl₂ / 12 h / Ambient temperature<br />2: 83 percent / PDc/Ac₂O activated molecular sives / CH₂Cl₂ / 0 deg C, then RT, 1 h<br /> <br /> &nbsp;