Ethyl isobutyrate → 1-phenylmethyl-alpha,alpha-dimethyl-4-hydroxy-4-piperidine-acetic Acid Ethyl Ester

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Reaction Conditions

Reaction Steps

125 ml of 1.6M butyllithium was added dropwise to a solution of 18.5 g (0.18 mole) of N-(1-methylethyl)-2-propanamine in 75 ml of tetrahydrofuran, cooled to a temperature of -70° C. The mixture was stirred for ten minutes at this temperature then 17.5 g ( 0.15 mole ) of 2-methyl-propanoic acid ethyl ester in solution in 70 ml of tetrahydrofuran was added, keeping the temperature at -70° C. After stirring for one hour at this temperature, a solution of 26 g (0.14 mole) of 1-phenylmethyl-4-piperidinone in 70 ml of tetrahydrofuran was added. The reaction medium was stirred for 1.5 h at a temperature of -70° C. and was then allowed to return to room temperature. After evaporating off the solvents under reduced pressure, the residue was poured into a saturated solution of ammonium chloride. The organic phase was extracted with ether, washed with water, dried over magnesium sulphate and filtered and the solvents were evaporated off under reduced pressure. After purification by distillation, 32 g (yield: 76%) of the desired product was obtained as an oil. B Pt=145°-150° C. (0.05 mm Hg, i.e. about 6.66 Pa)

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