Lithium aluminum tetrahydride (730 mg, 20 mmol) was suspended in tetrahydrofuran (10 ml), the product of Example 5 (3.2 g, 10 mmol) was dissolved in toluene, cooled in an ice-water bath, the solution of red aluminum in toluene (9 mL, 30 mmol) was added dropwise, the reaction was carried out for 2 hours and then quenched by adding 10% NaOH aqueous solution. After the reaction solution was separated, the organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated to give a pale yellow oil 2.8 g, yield: 90%. The HNMR spectrum data is the same as that in Example 6.
