in pyridine 2 h; Ambient temperature;

1: SnCl4 / 2 h / Ambient temperature 2: Et3N / CHCl3 / 2 h / Ambient temperature 3: 83.9 percent / piperidine, acetic acid / benzene / 5 h / Heating 4: 88.3 percent / pyridine / 2 h / Ambient temperature View Scheme

1: 83.9 percent / piperidine, acetic acid / benzene / 5 h / Heating 2: 88.3 percent / pyridine / 2 h / Ambient temperature View Scheme