dicyclohexyl-carbodiimide in dichloromethane T=4°C; 3 h;

1: 1 mg / 4-(dimethylamino)pyridine / pyridine / 16 h / 25 °C 2: 2.8 g / pyridine / 8 h / 0 °C 3: 1.8 g / DBU / pyridine / 3 h / Heating 4: 1.44 g / acetic acid; tetrahydrofuran; H2O / 8 h / 25 °C 5: 65 percent / pyridinium chlorochromate / CH2Cl2 / 4 h / 25 °C 6: 1.) NaH, 2.) n-BuLi / 1.) THF, 0 deg C, 10 min, 2.) THF-hexane, 0 deg C, 10 min, 3.) 0 deg C, 15 min 7: 34 mg / Zn(BH4)2 / diethyl ether / 1 h / 25 °C 8: 32 mg / p-toluenesulfonic acid monohydrate / benzene / 0.25 h / 25 °C View Scheme

1: 97 percent / Et3N / DMAP / CH2Cl2 / 88 h / Ambient temperature 2: 95 percent / Bu4NF / tetrahydrofuran / 3 h / Ambient temperature 3: 1.) (COCl)2; 2.) Et3N / 1.) DMSO, CH2Cl2, -78 deg C, 20 min; 2.) -78 deg C, 10 min, -78 deg C -> r.t., 20 min 4: 97 percent / 1.3N HCl / tetrahydrofuran / 4 h / Ambient temperature 5: 77 percent / Ag2CO3/Celite, PhMe / toluene / 1 h / 90 °C View Scheme

1: 32 percent / pyridine, 4-(N,N-dimethylamino)pyridine / 91 h / Ambient temperature 2: 1) (COCl)2, DMSO, 2) NEt3 / 1) CH2Cl2, -78 deg C, 25 min, 2a) -78 deg C, 5 min, b) to.r.t. 3: 77 percent / LiBr, NEt3 / acetonitrile / 16 h / Ambient temperature 4: 80 percent / nBu4NF*3H2O, HOAc / tetrahydrofuran / 48 h 5: 89 percent / H2 / 10percent Pd/C / ethyl acetate / 9 h View Scheme

Yield given. Multistep reaction;