acetic anhydride T=70°C; 3 h;

in acetic anhydride T=140°C; 1.5 h;

1: dicyclohexylcarbodiimide / acetonitrile / 24 h / Ambient temperature 2: 60 percent / hydrogen peroxide (40 percent) / acetic acid / 80 °C 3: 43 percent / acetic anhydride / 1.5 h / 140 °C View Scheme

1: dicyclohexylcarbodiimide / acetonitrile / 24 h / Ambient temperature 2: 60 percent / hydrogen peroxide (40 percent) / acetic acid / 80 °C 3: 43 percent / acetic anhydride / 1.5 h / 140 °C View Scheme

1: 60 percent / hydrogen peroxide (40 percent) / acetic acid / 80 °C 2: 43 percent / acetic anhydride / 1.5 h / 140 °C View Scheme