hydrogen; palladium on activated charcoal in methanol 1 h;

1: 1.) NaNO2, conc H2SO4, 2.) H2O / 1.) water, 1 h, 2.) 160 deg C, 10 min 2: 1.) trifluoroacetic acid, 2.) water / 1.) 80 deg C, 4 h, 2.) RT, 20 min 3: 82 percent / NaH, dicyclohexyl-18-crown-6 / toluene / 48 h / Ambient temperature 4: 95 percent / 0.1N aq. NaOH / methanol / 1.5 h View Scheme