toluene-4-sulfonic acid; hydroquinone in toluene 9 h; Heating / reflux;

1: nitromethane With 1,8-diazabicyclo[5.4.0]undec-7-ene in tetrahydrofuran T=20°C; deprotonation; 0.166667 h; 2: ethyl N-benzyloxycarbonyl-α-(tosyl)glycinate With 1,8-diazabicyclo[5.4.0]undec-7-ene in tetrahydrofuran T=-40°C; Addition; elimination;

trichlorophosphate in benzene 4 h; Heating;

triethylamine in tetrahydrofuran

1.1: 85 percent / air; formic acid / 48 h / 20 °C 2.1: 1,8-diazabicyclo[5.4.0]undec-7-ene / tetrahydrofuran / 0.17 h / 20 °C 2.2: 63 percent / 1,8-diazabicyclo[5.4.0]undec-7-ene / tetrahydrofuran / -40 °C View Scheme