trifluoroacetic acid in dichloromethane T=20°C; 1.5 h;

1.1: 50 percent / 2,6-lutidene / dimethylformamide / 20 h / 20 °C 2.1: phosphorous oxychloride / 2 h / 20 °C 2.2: 73 percent / dimethylformamide / 20 h / 20 °C 3.1: 20 percent / DABCO / benzene / 20 h / Heating 4.1: phosphorous oxychloride / 2 h / 20 °C 4.2: 57 percent / dimethylformamide / 20 h / 20 °C 5.1: 100 percent / trifluoroacetic acid / CH2Cl2 / 1.5 h / 20 °C View Scheme

1.1: phosphorous oxychloride / 2 h / 20 °C 1.2: 73 percent / dimethylformamide / 20 h / 20 °C 2.1: 20 percent / DABCO / benzene / 20 h / Heating 3.1: phosphorous oxychloride / 2 h / 20 °C 3.2: 57 percent / dimethylformamide / 20 h / 20 °C 4.1: 100 percent / trifluoroacetic acid / CH2Cl2 / 1.5 h / 20 °C View Scheme

1.1: 20 percent / DABCO / benzene / 20 h / Heating 2.1: phosphorous oxychloride / 2 h / 20 °C 2.2: 57 percent / dimethylformamide / 20 h / 20 °C 3.1: 100 percent / trifluoroacetic acid / CH2Cl2 / 1.5 h / 20 °C View Scheme

1.1: phosphorous oxychloride / 2 h / 20 °C 1.2: 57 percent / dimethylformamide / 20 h / 20 °C 2.1: 100 percent / trifluoroacetic acid / CH2Cl2 / 1.5 h / 20 °C View Scheme