sodium hydride in tetrahydrofuran T=0°C;

1: 2,2-dimethyl-5-hydroxymethyl-1,3-dioxane With oxalyl dichloride; dimethyl sulfoxide; triethylamine in dichloromethane T=-78 - 0°C; Swern oxidation; 2: ethyl (triphenylphosphoranylidene)acetate in dichloromethane T=20°C; Wittig olefination; 2 h; Further stages.;

1: PDC / CH2Cl2 / Heating 2: 404 mg / methanol / 20 °C View Scheme

1.1: p-TsOH / tetrahydrofuran 2.1: oxalyl chloride; DMSO; triethylamine / CH2Cl2 / -78 - 0 °C 2.2: 1.62 g / CH2Cl2 / 2 h / 20 °C View Scheme

in methanol T=20°C; Wittig olefination;

1: 100 percent / H2 / Pd/C / methanol / 8 h / 20 °C 2: 1.) sec-BuLi / 1.) THF, -78 deg C, 30 min, 2.) THF, 0 deg C, 1 h 3: 96 percent / p-TsOH*H2O / benzene / 5 h / 25 °C 4: 95 percent / LDA / tetrahydrofuran / -78 - 20 °C 5: 1.) DMAP, Et3N / 1.) CH2Cl2, 0 deg C, 10 min, 2.) CH2Cl2, 0 deg C, 5 h 6: 1.) O3, 2.) dimethyl sulfide / 1.) MeOH, -78 deg C, 2.) MeOH, 25 deg C, 1 h 7: NaClO2, NaH2PO4 / dimethylsulfoxide; H2O / 25 h / 25 °C 8: 15.6 mg / Raney Ni / ethanol / 0.08 h / 25 °C View Scheme