phenylhydrazine in methanol; acetic acid T=20°C; 24 h;

acetic acid in 1-methyl-pyrrolidin-2-one; methanol T=50°C; 5 h;

1.1: pyridinium tribromide / acetonitrile / 1 h / 10 - 15 °C 1.2: 94 percent / water / acetonitrile; methanol / 0.25 h / 10 - 15 °C 2.1: 97 percent / 1-methyl-pyrrolidin-2-one / 48 h / 20 °C 3.1: 80 percent / phenyl hydrazine / methanol; acetic acid / 24 h / 20 °C View Scheme

1: 97 percent / 1-methyl-pyrrolidin-2-one / 48 h / 20 °C 2: 80 percent / phenyl hydrazine / methanol; acetic acid / 24 h / 20 °C View Scheme