Tetrahydrofuran → 4-Methoxyphenol

12.7 g of 4-arm PEG 2 k (Mn=2323 g/mol, 21.9 meq OH) were dissolved in 250 ml of dry tetrahydrofuran under an Ar atmosphere. The solution was dried by refluxing the solvent over molecular sieves until the water content had fallen below 100 ppm, after which it was allowed to cool down to room temperature. 2.81 g of triethylamine (27.8 mmol) were added and a solution of 2.51 g of acryloylchloride (27.7 mmol) in 25 ml of dry dichloromethane was added drop wise at such a rate that the temperature of the reaction mixture remained below 30° C. The resulting suspension was filtered through ca. 1.5 cm of Celite 545, yielding a pale yellow, clear solution to which 44 mg of MEHQ were added. The solvent was removed by rotary evaporation, the remaining oil was redissolved in 150 ml of water and NaHCO3 was added until pH 8. The aqueous solution was washed three times with 50 ml of diethyl ether, 15 g of NaCl were added and the product was extracted with five 50 ml portions of dichloromethane. The combined organic layers were dried with Na2SO4, and filtered. Removing the solvent by rotary evaporation yielded 12.9 g (93%) of a yellow oil. The structure of the product was confirmed by 1H NMR, which showed a degree of functionalization of ca. 95%.