1: 57 percent / pyridinium chlorochromate / CH2Cl2 / 1.5 h / other reagent 2: 1.) n-butyl-lithium, TMEDA 2.) n-butyl-lithium / 1.) hexane, THF, 0 deg C, 15 min 2.) 30 min, hexane, THF 3: 23 percent / toluene-p-sulphonic acid / benzene / 0.02 h View Scheme

1: 57 percent / pyridinium chlorochromate / CH2Cl2 / 1.5 h / other reagent 2: 1.) n-butyl-lithium, TMEDA 2.) n-butyl-lithium / 1.) hexane, THF, 0 deg C, 15 min 2.) 30 min, hexane, THF 3: 23 percent / toluene-p-sulphonic acid / benzene / 0.02 h 4: 64 percent / MCPBA / ethanol / 0.5 h / 0 °C 5: 77 percent / Heating View Scheme

1: (i) 2-chloro-benzo<1,3,2>dioxaphosphole, Py, Et2O, (ii) I2, CH2Cl2 2: (i) nBuLi, THF, (ii) PhSH, MeOH View Scheme