1: formic acid / 18 h / 115 °C 2: NaClO2; NH2SO3H / methanol; H2O / 1.5 h / 20 °C View Scheme

potassium tert-butylate in tetrahydrofuran; N,N-dimethyl-formamide T=-78°C; 0.166667 h;

1: 95 percent / K2CO3 / dimethylformamide / 4 h / 75 °C 2: 72 percent / t-BuOK / dimethylformamide; tetrahydrofuran / 0.17 h / -78 °C View Scheme

formic acid T=115°C; 18 h;

1.1: formic acid / 18 h / 115 °C 2.1: NaClO2; NH2SO3H / methanol; H2O / 1.5 h / 20 °C 3.1: CDI / tetrahydrofuran / 1 h / Heating 3.2: 68 percent / t-BuOK / 0 - 5 °C 4.1: 95 percent / Fe; HCl / ethanol / 20 h / Heating View Scheme

1.1: formic acid / 18 h / 115 °C 2.1: NaClO2; NH2SO3H / methanol; H2O / 1.5 h / 20 °C 3.1: CDI / tetrahydrofuran / 1 h / Heating 3.2: 68 percent / t-BuOK / 0 - 5 °C View Scheme