To a solution of pravastatin sodium (9.25 g, 21 mmol) in N,N-dimethylformamide (70 ml) a mixture of 1,4-dibromobutane (3.68 ml, 31 mmol) in N,N-dimethylformamide (30 ml) was added dropwise. The reaction mixture was stirred at room temperature for 24 h. The solution was then treated with water and diethyl ether, the organic layers were dried with sodium sulfate and concentrated under reduced pressure. The residue was purified by flash chromatography, with n-hexane/ethyl acetate 3/7 as eluent. The title compound was obtained as a white powder (7.8 g).
