Hexamethylphosphoramide → Methyl 3-cyclopentyl-2-methyl-2-phenylpropanoate

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A solution of lithium bis(trimethylsilyl)amide (1M in tetrahydrofuran, 3.04 mL, 3.04 mmol, 1 equiv) under a N2 atmosphere was cooled to 0° C. and treated with a solution of methyl 2-phenylpropionate (0.500 g, 3.04 mmol, 1 equiv) in dry tetrahydrofuran (2 mL). The reaction was stirred at 0° C. for 2 hrs, then cooled to −78° C. and treated with hexamethylphosphoric triamide (0.4 mL) and bromomethylcyclopentane (0.745 g, 4.568 mmol, 1.5 equiv). Stirred the reaction at −78° C. and allowed the bath to slowly warm to room temperature overnight. After 15 hrs, the reaction mixture was quenched with 10% aq NH4Cl (50 mL) and extracted with ethyl acetate (100 mL). The organic extract was washed with H2O (50 mL) and brine, then dried over Na2SO4, filtered, and concentrated by rotary evaporation. The residue was purified by SiO2 flash chromatography with 2:3 dichloromethane/hexanes to give the product as colorless oil (1.38 g, 5.60 mmol, 92%). 1H NMR (300 MHz, DMSO-d6): δ ppm 0.90-1.12 (m, 2H) 1.32-1.72 (m, 10H) 1.97-2.12 (m, 2H) 3.58 (s, 3H) 7.19-7.35 (m, 5H); MS (APCI+) m/z 247 (M+H)+.

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