sodium hydroxide in methanol T=25°C; 24 h;

1: 1-phenyl-2(1H,3H)-indolone With sodium hydroxide in tetrahydrofuran T=67°C; 5 h; 2: methyl chloroformate With n-butyllithium in tetrahydrofuran; cyclohexane T=-40°C; 2 h; 3: With hydrogenchloride in tetrahydrofuran; cyclohexane; water

1: 1-phenyl-2(1H,3H)-indolone With sodium hydroxide in tetrahydrofuran T=67°C; 5 h; 2: carbonic acid dimethyl ester With n-butyllithium in tetrahydrofuran; cyclohexane T=-10°C; 2 h; 3: With hydrogenchloride in tetrahydrofuran; cyclohexane; water

1.1: pyridine / toluene / 24 h / 50 °C 1.2: pyridine / 22 h / 100 °C 2.1: 90 percent / aq. NaOH / methanol / 24 h / 25 °C View Scheme

1.1: sodium hydroxide / water; ethanol / 1 h / 50 °C 1.2: 4 h / 20 °C 2.1: pyridine / toluene / 24 h / 50 °C 3.1: pyridine / 22 h / 100 °C 4.1: sodium hydroxide / water; methanol / 24 h / 20 °C View Scheme

PPA T=95°C; 3 h;

1: 70 percent / polyphosphoric acid / 3 h / 95 °C 2: 81 percent / p-TsOH / methanol / 5 h / Heating 3: 98 percent / aq. NaOH / various solvent(s) / 4 h / 100 °C 4: AcOH / 7 h / 25 °C View Scheme

1.1: polyphosphoric acid / 3 h / 95 °C 2.1: 97 percent / aq. NaOH / 6 h / 100 °C 3.1: 98 percent / dimethylformamide / 4 h / 24 °C 4.1: 98 percent / Et3N; DMAP / CH2Cl2 / 3.5 h / 20 - 40 °C 5.1: 95 percent / hydrogen / Pd/C / methanol / 3 h / 30 °C 6.1: 40 percent / polyphosphoric acid / toluene / 11 h / 110 °C 7.1: aq. Na2CO3 / methanol; H2O / 0.5 h / 23 °C 8.1: CH2Cl2 / 17 h / 25 °C 8.2: 70 percent / H2O View Scheme

1: polyphosphoric acid / 3 h / 95 °C 2: 97 percent / aq. NaOH / 6 h / 100 °C 3: acid / pH 2 View Scheme

polyphosphoric acid T=90 - 95°C; 3 h;