[OH:1][C:2]1[C:3]([CH3:15])=[C:4]2[C:9](=[C:10]([CH3:13])[C:11]=1[CH3:12])[O:8][C:7](=[O:14])[CH2:6][CH2:5]2.[CH:16]([Si:19](Cl)([CH:23]([CH3:25])[CH3:24])[CH:20]([CH3:22])[CH3:21])([CH3:18])[CH3:17].N1C=CN=C1>CN(C=O)C.C(OCC)(=O)C>[CH3:15][C:3]1[C:2]([O:1][Si:19]([CH:23]([CH3:25])[CH3:24])([CH:20]([CH3:22])[CH3:21])[CH:16]([CH3:18])[CH3:17])=[C:11]([CH3:12])[C:10]([CH3:13])=[C:9]2[C:4]=1[CH2:5][CH2:6][C:7](=[O:14])[O:8]2A solution of 6-hydroxy-5,7,8-trimethyl-chroman-2-one (1.22 g), triisopropylsilyl chloride (1.71 g) and imidazole (806 mg, 11.84 mmol) in anhydrous DMF (2 mL) was stirred at room temperature for two days. The solution was diluted with ethyl acetate, washed with water and brine. Evaporation and chromatography (silica gel, hexane-ethyl acetate) gave 1.25 g of 5,7,8-trimethyl-6-triisopropylsilanyloxy-chroman-2-one.
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