1: 47 percent / pyridine, TsCl / 1) 40 h, r.t. 2) reflux, 2 h 2: 83 percent / Ag2CO3/Celite / benzene / 0.67 h / 110 - 120 °C 3: 91 percent / diethyl ether / 1 h / Heating 4: 4 percent / TsOH*H2O, AcOH / 0.5 h / Heating View Scheme

1: 47 percent / pyridine, TsCl / 1) 40 h, r.t. 2) reflux, 2 h 2: 83 percent / Ag2CO3/Celite / benzene / 0.67 h / 110 - 120 °C 3: 63 percent / benzene; pentane / Heating 4: 4 percent / TsOH*H2O, AcOH / 0.5 h / Heating View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1: 96 percent / pyridinium chlorochromate / CH₂Cl₂ / 1.5 h / Ambient temperature<br />2: 67 percent / 2,6-di-t-butyl-4-methylpyridine, triflic acid / CCl₄ / 0 &deg;C<br />3: 85 percent / KOH / methanol / 2 h / Heating<br /> <br /> &nbsp;