1: 83 percent / polyphosphoric acid / toluene / 4 h / Heating 2: 95 percent / tetrabutylammonium hydrogen sulfate, aq. NaOH / CH2Cl2 / 0.5 h 3: 58 percent / pyridine hydrochloride / 0.5 h / 210 °C 4: 90 percent / K2CO3 / acetone / 3 h / Heating 5: 1.) BuLi / 1.) THF, -70 deg C, 1 h, 2.) THF, RT, 18 h 6: conc. HCl / ethanol / 1 h / Heating View Scheme

1: 83 percent / polyphosphoric acid / toluene / 4 h / Heating 2: 95 percent / tetrabutylammonium hydrogen sulfate, aq. NaOH / CH2Cl2 / 0.5 h 3: 58 percent / pyridine hydrochloride / 0.5 h / 210 °C 4: 60 percent / K2CO3 / acetone; dimethylformamide / 18 h / Heating 5: 1.) BuLi / 1.) THF, -70 deg C, 1 h, 2.) THF, RT, 18 h 6: 68 percent / conc. HCl / ethanol / 1 h / Heating View Scheme

1: 83 percent / polyphosphoric acid / toluene / 4 h / Heating 2: 95 percent / tetrabutylammonium hydrogen sulfate, aq. NaOH / CH2Cl2 / 0.5 h 3: 58 percent / pyridine hydrochloride / 0.5 h / 210 °C 4: 60 percent / K2CO3 / acetone; dimethylformamide / 18 h / Heating 5: 1.) BuLi / 1.) THF, -70 deg C, 1 h, 2.) THF, RT, 18 h 6: conc. HCl / ethanol / 1 h / Heating View Scheme

1: 83 percent / polyphosphoric acid / toluene / 4 h / Heating 2: 95 percent / tetrabutylammonium hydrogen sulfate, aq. NaOH / CH2Cl2 / 0.5 h 3: 58 percent / pyridine hydrochloride / 0.5 h / 210 °C 4: 90 percent / K2CO3 / acetone / 3 h / Heating 5: 1.) BuLi / 1.) THF, -70 deg C, 1 h, 2.) THF, RT, 18 h 6: conc. HCl / ethanol / 1 h / Heating View Scheme

1: 83 percent / polyphosphoric acid / toluene / 4 h / Heating 2: 95 percent / tetrabutylammonium hydrogen sulfate, aq. NaOH / CH2Cl2 / 0.5 h 3: 58 percent / pyridine hydrochloride / 0.5 h / 210 °C 4: 90 percent / K2CO3 / acetone / 3 h / Heating 5: 1.) BuLi / 1.) THF, -70 deg C, 1 h, 2.) THF, RT, 18 h 6: conc. HCl / ethanol / 1 h / Heating 7: 1.) OsO4, 2.) H2S / 1.) THF, RT, 18 h View Scheme