Methyl (2S)-1-methyl-5-oxoprolinate → (5S)-5-(Hydroxymethyl)-1-methyl-2-pyrrolidinone

A stirred solution of 0.68 g (4.33 mmole) (S)-Methyl 1-methyl-5-oxopyrrolidine-2-carboxylate in 15 ml dry tetrahydrofuran was cooled to −78° C. and under argon atmosphere, 2.2 ml (2.2 mmole) of 1M lithium aluminum hydride solution in tetrahydrofuran was added drop by drop during 20 minutes, stirred at −78° C. for 1 hour and removing the cooling bath left to warm up to 0° C. at stirring. While ice cooling, 0.22 ml 10% of sodium hydroxide aqueous solution was added, stirred for 10 minutes, then 0.22 ml of water was added and the reaction mixture stirred for 1.5 hours allowing it to warm to room temperature. The precipitate was filtered and washed with 5×2 ml of ethyl acetate. The combined filtrates were dried over magnesium sulfate and evaporated at 35° C. in good vacuum, giving 0.52 g (93%) product which was pure enough for the next step.