1: benzimidazole-5,6-dicarboxylic acid anhydride With trimethylsilylazide T=95°C; 2: S-methylisothiourea sulfate With water in tetrahydrofuran

1: 48 percent / KMnO4 / H2O; 2-methyl-propan-2-ol / 70 °C 2: 93 percent / 3 h / 145 - 150 °C 3: 1.)azidotrimethylsilane, 2.) cyanamide, t-BuOK / 1.) CH3CN, from 90 deg C to 95 deg C, 3 h, 2.) DMF, 155 deg C, 3 h View Scheme

1: 93 percent / 3 h / 145 - 150 °C 2: 1.)azidotrimethylsilane, 2.) cyanamide, t-BuOK / 1.) CH3CN, from 90 deg C to 95 deg C, 3 h, 2.) DMF, 155 deg C, 3 h View Scheme