Ethyl acetate hexane → (S)-2-(dibenzylamino)pentanal

Participants

Reaction Steps

To anhydrous tetrahydrofuran (1.5 L) previously cooled to −20° C. to −30° C. was added solid lithium aluminum hydride (33.5 g; 0.882 mol; 120 mole %) slowly with stirring. A solution of (S)-2-(dibenzylamino)-N-methoxy-N-methylpentanamide (6) (250 g; 0.735 mol) in anhydrous tetrahydrofuran (1 L) at −30° C. was slowly added to the above mixture under a nitrogen atmosphere. The reaction was continued for 2 hours at −30° C., monitoring progress of the reaction by TLC analysis (ethyl acetate/hexane, 1:9). Upon completion of the reaction, the excess reagent was quenched by the dropwise addition of ethyl acetate (1 L) and ice-cold water (300 ml) at −30° C. The insoluble salts were filtered through celite, the filtrate diluted with water (3 L), and the product extracted into ethyl acetate (2 L). The combined ethyl acetate layers were washed with water (2 L), dried over sodium sulfate, filtered, and solvent removed under reduced pressure to provide (S)-2-(dibenzylamino)pentanal (7) (195 g) as a light yellow oil, which was used without purification in the next step.

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