1: 1.) Mg / 1.) THF, reflux, 2.) reflux, 4 h 2: p-toluenesulfonic acid / benzene / 0.5 h / Heating 3: p-toluenesulfonic acid / methanol / 24 h / Ambient temperature 4: Zn / diethyl ether / 0.5 h / Heating 5: Zn, NH4Cl / methanol / 3 h / Heating 6: molecular sieves 3A, pyridine / 72 h / Ambient temperature 7: 1.) p-toluenesulfonyl chloride, 2.) H2O / 1.) pyridine, 0 deg C, 15 h, 2.) overnight 8: 94 percent / K2CO3 / methanol / 3 h / Ambient temperature 9: 90 percent / BH3*THF / tetrahydrofuran / 2 h / Heating 10: 91 percent / Jones reagent / acetone / 0.33 h / 0 °C 11: 71 percent / base / acetone View Scheme

toluene-4-sulfonic acid in dichloromethane 1.5 h; ice-bath;

oxalyl dichloride; dimethyl sulfoxide in tetrahydrofuran T=-60 - -50°C; 0.25 h;

in tetrahydrofuran

in 1,4-dioxane; water; dimethyl sulfoxide 14 h; Heating;

1: 48 percent / pyridinium p-toluenesulfonate / CH2Cl2; tetrahydrofuran / 24 h / 20 °C 2: (COCl)2; DMSO; Et3N / CH2Cl2 / -60 - 20 °C View Scheme

1: 93 percent / PPTS / tetrahydrofuran / 6 h / Ambient temperature 2: 87 percent / oxalyl chloride, DMSO / tetrahydrofuran / 0.25 h / -60 - -50 °C View Scheme

jones reagent; toluene-4-sulfonic acid 1) acetone, 1 h, ice-bath cooling, 2) CH2Cl2, 30 min, rt; Yield given. Multistep reaction. Yields of byproduct given;

1: 78 percent / diethyl ether / 1 h / Ambient temperature 2: 61 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 60 - 70 °C 3: 88 percent / pyridinium chlorochromate (PCC), NaOAc / CH2Cl2 / 8 h / Ambient temperature View Scheme

1: 78 percent / diethyl ether / 1 h / Ambient temperature 2: 61 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 60 - 70 °C 3: 88 percent / pyridinium chlorochromate (PCC), NaOAc / CH2Cl2 / 8 h / Ambient temperature 4: 84 percent / dimethylformamide / 80 °C 5: 1) lithium diisopropylamide / 1) THF, -60 deg C, 20 min, 2) -60 to -5 deg C 6: 1) lithium diisopropylamide / 1) THF, -70 deg C, 15 min, 2) -70 deg C, 1 h 7: 30 percent aq. acetic acid / tetrahydrofuran / 3 h / Ambient temperature 8: 71 percent / triethylamine, 4-dimethylaminopyridine / 48 h / Ambient temperature 9: 40 percent / triethylamine, 4-dimethylaminopyridine / 7 h / ice-NaCl bath 10: 70 percent / aq. acetic acid / tetrahydrofuran / 4 h / Ambient temperature View Scheme