1: 93 percent / imidazole / CH2Cl2; dimethylformamide / 1.) RT, 15 h, 2.) 45 deg C, 20 h, 3.) 80 deg C, 6 h 2: 1.) ozone, 2.) NaBH4 / 1.) MeOH, pyridine, CH2Cl2, -78 deg C, 1 h, 2.) RT, 12 h 3: 95 percent / 48percent aq. HF / acetonitrile / 1.5 h / Ambient temperature View Scheme

1: py-DMAP 2: 1.) 03, 2.) P(OEt)3 / 1.) MeOH-CH2Cl2-py, -80 deg C 3: 97 percent / BF3.OEt2 / tetrahydrofuran / 16 h / 0 °C 4: TiCl4 / CH2Cl2 / 0.08 h 5: PCC / CH2Cl2 / 8 h / 0 °C 6: EtN(i-Pr)2-DMAP / CH2Cl2 / 1.) 0 deg C, 2.) 18 h, RT 7: K2CO3 / methanol / 3 h / Ambient temperature View Scheme

1: 93 percent / imidazole / CH2Cl2; dimethylformamide / 1.) RT, 15 h, 2.) 45 deg C, 20 h, 3.) 80 deg C, 6 h 2: 1.) ozone, 2.) NaBH4 / 1.) MeOH, pyridine, CH2Cl2, -78 deg C, 1 h, 2.) RT, 12 h 3: 95 percent / pyridine / 2 h / 0 °C View Scheme

1: 95 percent / DMAP, pyridine / 14 h / refrigerator 2: 95 percent / pyridine, ozone / methanol; CH2Cl2 / 0.42 h / -78 °C 3: 1) 2,6-di-tert-butylpyridine, 2a) TMSTf, 2b) Et3N, MeOH / 1) CH2Cl2, -78 deg C, 5 min, 2a) -78 deg C, 2 h, 2b) -78 deg C, 5 min then to RT 4: TiCl4 / CH2Cl2 / 12 h / -78 °C 5: 92 percent / DMAP, i-Pr2NEt / CH2Cl2 / 18 h / 0 °C 6: 91 percent / LDA / tetrahydrofuran / 0.5 h / -78 °C 8: 1) LDA / 1) -78 deg C 9: 94 percent / Et3N / (Ph3P)2PdCl2 / 75 °C 10: H2, Lindlar catalyst, quinoline / hexane 11: 2,2,4-trimethyl-pentane / Heating 12: 82 percent / ion-exchange resin AG 50W-X4 / methanol / 48 h / Ambient temperature; in the dark View Scheme