Acetic Acid → 8-Isopropyl-2,2,4,4-tetramethyl-chroman-6-carboxylic acid 4-(2-carboxy-vinyl)-phenyl ester

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Reaction Steps

A suspension of t-butyldimethyl silane (0.3 mL, 1.85 mmol), palladium(II)acetate (0.013 g, 0.06 mmol) and triethyl amine (0.03 mL, 0.2 mmol) in anhydrous dichloromethane (2 mL) under argon was treated with a solution of 8-isopropyl-2,2,4,4-tetramethyl-chroman-6-carboxylic acid 4 (2-benzyloxycarbonyl-vinyl)-phenyl ester (Intermediate 35, 0.063 g, 0.123 mmol) in dichloromethane (2 mL) and the resulting reaction mixture was stirred overnight at ambient temperature. The reaction mixture was quenched with water and extracted with diethyl ether. The organic extract was dried over anhydrous sodium sulfate, filtered and evaporated to a residue that was subjected to flash column chromatography to yield an intermediate that was treated with acetic acid (1 mL) in water (0.3 mL) and tetrahydrofuran (0.3 mL) at ambient temperature for 1 h. The reaction mixture was diluted with water and extracted with ethyl acetate. The organic extract was dried over anhydrous sodium sulfate, filtered and evaporated to a residue that was subjected to preparative reverse phase HPLC using 10% water in acetonitrile as the mobile phase to afford the title compound (0.007 g).

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