[Br:1][C:2]1[CH:10]=[CH:9][C:5]([CH2:6][CH2:7][OH:8])=[CH:4][CH:3]=1.[CH3:11][C:12](OI1(OC(C)=O)(OC(C)=O)OC(=O)C2C=CC=CC1=2)=[O:13].C(O)CO>C(Cl)Cl.C1(C)C=CC=CC=1.O.C1(C)C=CC(S(O)(=O)=O)=CC=1>[Br:1][C:2]1[CH:10]=[CH:9][C:5]([CH2:6][CH:7]2[O:13][CH2:12][CH2:11][O:8]2)=[CH:4][CH:3]=1To a cooled (0° C.) solution of 4-bromophenethylalcohol (3.9 g, 19.4 mmol) in DCM (50 mL), was added the Dess-Martin reagent (8.22 g, 19.4 mmol). After 10 minutes, the coolant was removed, and the reaction mixture was stirred at ambient temperature for 2 hours. The reaction mixture was quenched with 10% aqueous potassium carbonate, and the mixture was separated. The aqueous phase was extracted with further DCM (×2), and the combined organic phases were dried with anhydrous magnesium sulphate, and the solvent evaporated at reduced pressure. The crude material was purified by silica gel chromatography eluting with 100% iso-hexane to 50% ethyl acetate in iso-hexane to afford a oil. The oil was dissolved in toluene (35 mL), para-toluenesulfonic acid—monohydrate (0.1 g, 0.52 mmol) and ethylene glycol (5.3 mL, 94.2 mmol) was added, and the mixture heated at reflux under Dean and Stark conditions for 2 hours. The solvent was evaporated at reduced pressure and the residue dissolved in ethyl acetate. The solution was washed with 10% aqueous potassium carbonate, dried with anhydrous magnesium sulfate, and the solvent evaporated at reduced pressure. The crude material was purified by silica gel chromatography eluting with 100% iso-hexane to 50% ethyl acetate in iso-hexane to afford an oil (2.3 g, 49%).
Wird geladen…
