Acetic Acid → 4-(5-Cyclopropylamino-8,8-dimethyl-5,6,7,8-tetrahydro-naphthalene-2-ylethynyl)-benzoic acid ethyl ester

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Reaction Steps

A solution of 4-(8,8-dimethyl-5-oxo-5,6,7,8-tetrahydro-naphthalene-2-ylethynyl)-benzoic acid ethyl ester (Intermediate 14, 0.14 g, 0.4 mmol) in 3 mL of dichloromethane and 2 mL of acetonitrile was treated with cyclopropyl amine(1 mL, 14.45 mmol). After 5 minutes, acetic acid (1 mL) was added followed by sodium cyanoborohydride (0.13 g, 2 mmol). The reaction was stirred overnight at ambient temperature. It was then diluted with water and saturated aqueous sodium carbonate solution and extracted with dichloromethane (×2). The combined organic extract was dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to an oil. Flash column chromatography over silica gel (230-400 mesh) using 20% ethyl acetate in hexane as the eluent afforded the title compound (0.1 g, 62%) as a pale yellow solid.

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