1: 77 percent / polystyrene bead C36H52N4O5 / toluene / 6 h / -40 °C 2: 98 percent / 0.17 h 3: 95 percent / aq. HCl / 3 h / 105 °C 4: 100 percent / H2; aq. HCl / Pd-C / methanol / 10 h / atmospheric pressure View Scheme