1: 83 percent / K2CO3 / acetone / 41 °C 2: pyridinium toluene-p-sulfonate, EtOH / 3 h / 55 °C View Scheme

1: 83 percent / K2CO3 / acetone / 41 °C 2: pyridinium toluene-p-sulfonate, EtOH / 3 h / 55 °C 3: 77 percent / KBrO3, HBr / acetic acid / 4 h / Ambient temperature 4: 96 percent / pyridinium toluene-p-sulfonate / CH2Cl2 / 4 h / Ambient temperature 5: 1.) n-BuLi, 2.) HCl, H2O / 1.) THF, hexane, -78 deg C, 45 min; 2 h, 2.) THF, hexane, r.t., 1 h View Scheme

1.1: caesium carbonate / acetonitrile / 3 h / |Inert atmosphere; |Reflux 1.2: |Inert atmosphere; |Reflux 2.1: hydrogenchloride / dichloromethane; methanol; water View Scheme

(i) NaH, DMF, (ii) aq. AcOH; Multistep reaction;

1: potassium carbonate / N,N-dimethyl-formamide / 4 h / 80 °C 2: pyridinium p-toluenesulfonate / ethanol / 2 h / 55 °C View Scheme

1: (i) NaH, DMF, (ii) aq. AcOH 2: (i) POCl3, dihydropyran, Et2O, (ii) /BRN= 878140/, K2CO3, nBuOH, (iii) aq. AcOH View Scheme

1.1: caesium carbonate / acetonitrile / 3 h / |Inert atmosphere; |Reflux 1.2: |Inert atmosphere; |Reflux 2.1: hydrogenchloride / dichloromethane; methanol; water View Scheme