caesium carbonate in 1,4-dioxane T=80°C; 36 h;

1: 97 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, triethylamine / dimethylformamide / 16 h 2: 40 percent / trifluoroacetic acid / CHCl3 / 2.5 h 3: 93 percent / 20percent aq. NaOH / ethanol / 16 h / Heating 4: 66 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, N-methylmorpholine / dimethylformamide / 17 h 5: 8.5 g / tetra-n-butylammonium fluoride / tetrahydrofuran / 20 h 6: 98 percent / H2 / 10percent Pd/C / tetrahydrofuran; methanol / 96 h 7: 98.9 percent / Cs2CO3 / dioxane / 36 h / 80 °C View Scheme

1: 88 percent / aq. H2SO4 / H2O / 16 h / Heating 2: 97 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, triethylamine / dimethylformamide / 16 h 3: 40 percent / trifluoroacetic acid / CHCl3 / 2.5 h 4: 93 percent / 20percent aq. NaOH / ethanol / 16 h / Heating 5: 66 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, N-methylmorpholine / dimethylformamide / 17 h 6: 8.5 g / tetra-n-butylammonium fluoride / tetrahydrofuran / 20 h 7: 98 percent / H2 / 10percent Pd/C / tetrahydrofuran; methanol / 96 h 8: 98.9 percent / Cs2CO3 / dioxane / 36 h / 80 °C View Scheme

1: 40 percent / trifluoroacetic acid / CHCl3 / 2.5 h 2: 93 percent / 20percent aq. NaOH / ethanol / 16 h / Heating 3: 66 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, N-methylmorpholine / dimethylformamide / 17 h 4: 8.5 g / tetra-n-butylammonium fluoride / tetrahydrofuran / 20 h 5: 98 percent / H2 / 10percent Pd/C / tetrahydrofuran; methanol / 96 h 6: 98.9 percent / Cs2CO3 / dioxane / 36 h / 80 °C View Scheme

1: 8.5 g / tetra-n-butylammonium fluoride / tetrahydrofuran / 20 h 2: 98 percent / H2 / 10percent Pd/C / tetrahydrofuran; methanol / 96 h 3: 98.9 percent / Cs2CO3 / dioxane / 36 h / 80 °C View Scheme

1: 93 percent / 20percent aq. NaOH / ethanol / 16 h / Heating 2: 66 percent / 1-hydroxybenzotriazole hydrate, dimethyl-3-<3-(dimethylamino)propyl>carbodiimide hydrochloride, N-methylmorpholine / dimethylformamide / 17 h 3: 8.5 g / tetra-n-butylammonium fluoride / tetrahydrofuran / 20 h 4: 98 percent / H2 / 10percent Pd/C / tetrahydrofuran; methanol / 96 h 5: 98.9 percent / Cs2CO3 / dioxane / 36 h / 80 °C View Scheme

methanol; camphor-10-sulfonic acid

2: camphorsulfonic acid, MeOH View Scheme

2: camphorsulfonic acid, MeOH View Scheme