1: 91 percent / pyridine / CH2Cl2 / 0.5 h / Ambient temperature 2: 100 percent / 1 h / 90 °C 3: 80 percent / pyridine / 72 h / 110 °C 4: 2) Amberlite IRA-410 / 1) 39 h, reflux, 2) MeOH, H2O View Scheme

1: 100 percent / 1 h / 90 °C 2: 80 percent / pyridine / 72 h / 110 °C 3: 2) Amberlite IRA-410 / 1) 39 h, reflux, 2) MeOH, H2O View Scheme

1: 100 percent / 1 h / 90 °C 2: 80 percent / pyridine / 72 h / 110 °C 3: 2) Amberlite IRA-410 / 1) 39 h, reflux, 2) MeOH, H2O View Scheme

1: 80 percent / pyridine / 72 h / 110 °C 2: 2) Amberlite IRA-410 / 1) 39 h, reflux, 2) MeOH, H2O View Scheme

Amberlite IRA-410 1) 39 h, reflux, 2) MeOH, H2O; Yield given. Multistep reaction;