1.1: 93 percent / HCl / ethyl acetate / 2 h / 20 °C 2.1: 1-hydroxybenzotriazole hydrate; N,N'-dicyclohexylcarbodiimide / tetrahydrofuran / 0.5 h / 0 °C 2.2: 89 percent / N-methylmorpholine / tetrahydrofuran / 8 h / 20 °C / pH 8.5 3.1: 93 percent / HCl / ethyl acetate / 3 h / 20 °C 4.1: 92 percent / H2; formic acid / Pd/C / methanol / 24 h / 20 °C / 150.01 Torr View Scheme