1: 91 percent / triethylamine, dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBT) H2O / dimethylformamide; CH2Cl2 / 4 h / 0 °C 2: 98 percent / H2 / 5percent PdC / methanol 3: 1.) N-methylmorpholine, isobutyl chloroformate / 1.) THF, -15 - -10 deg, 15 min., 2.) THF, DMF, a) -15 - -10 deg, 2h, b) RT, overnight 4: 86 percent / NaOH / dimethylformamide; acetone / 1 h / Ambient temperature 5: 1.) N-methylmorpholine, isobutyl chloroformate, 2.) N-methylmorpholine / 1.) THF, -15 - -10 deg, 15 min., 2.) THF, DMF, a) -15 - -10 deg, 2h, b) RT, overnight 6: 94 percent / CH2Cl2 / 0.5 h / Ambient temperature View Scheme