hydrogen; palladium on activated charcoal in methanol Hydrogenolysis; debenzylation; P=760.051 Torr; 1 h;

trifluoroacetic acid in dichloromethane T=20°C; Cooling with ice;

1.1: NaNO2; 2.5N H2SO4 / H2O / 0 - 20 °C 2.1: Cs2CO3 / methanol; H2O / pH 7 2.2: 94 percent / dimethylformamide / 6 h / 20 °C 3.1: 99 percent / PPh3; DIAD / CH2Cl2 / 0.67 h / -40 - -20 °C 4.1: 68 percent / H2 / Pd/C / methanol / 1 h / 760.05 Torr View Scheme

1.1: Cs2CO3 / methanol; H2O / pH 7 1.2: 94 percent / dimethylformamide / 6 h / 20 °C 2.1: 99 percent / PPh3; DIAD / CH2Cl2 / 0.67 h / -40 - -20 °C 3.1: 68 percent / H2 / Pd/C / methanol / 1 h / 760.05 Torr View Scheme

1: 99 percent / PPh3; DIAD / CH2Cl2 / 0.67 h / -40 - -20 °C 2: 68 percent / H2 / Pd/C / methanol / 1 h / 760.05 Torr View Scheme