toluene-4-sulfonic acid in benzene 9 h; Heating;

1.1: POCl3 / 0.25 h / cooling 1.2: 85 percent / dimethylformamide / 100 - 110 °C 2.1: 80 percent / N-bromosuccinimide / acetonitrile / 0 - 20 °C 3.1: 90 percent / PTSA monohydrate / benzene / 9 h / Heating View Scheme

1: 80 percent / N-bromosuccinimide / acetonitrile / 0 - 20 °C 2: 90 percent / PTSA monohydrate / benzene / 9 h / Heating View Scheme

Multistep reaction;