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

1: 95 percent / pyridine, ozone / methanol; CH2Cl2 / 0.42 h / -78 °C 2: 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 3: TiCl4 / CH2Cl2 / 12 h / -78 °C 4: 92 percent / DMAP, i-Pr2NEt / CH2Cl2 / 18 h / 0 °C 5: 91 percent / LDA / tetrahydrofuran / 0.5 h / -78 °C 7: 1) LDA / 1) -78 deg C 8: 94 percent / Et3N / (Ph3P)2PdCl2 / 75 °C 9: H2, Lindlar catalyst, quinoline / hexane 10: 2,2,4-trimethyl-pentane / Heating 11: 82 percent / ion-exchange resin AG 50W-X4 / methanol / 48 h / Ambient temperature; in the dark View Scheme

Multi-step reaction with 2 steps 1: 95 percent / pyridine, ozone / methanol; CH2Cl2 / 0.42 h / -78 °C2: 1) s-collidine, 2) NaBH4 / 1) reflux, 48 h, 2) MeOH, 15 min  

Multi-step reaction with 6 steps 1: 95 percent / pyridine, ozone / methanol; CH2Cl2 / 0.42 h / -78 °C2: 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 RT3: TiCl4 / CH2Cl2 / 12 h / -78 °C4: 92 percent / DMAP, i-Pr2NEt / CH2Cl2 / 18 h / 0 °C5: 91 percent / LDA / tetrahydrofuran / 0.5 h / -78 °C