Dicyclohexylcarbodiimide → Benzyl N-(2-oxopentanoyl)prolinate

Participants

Reaction Steps

8.8 g benzyl prolinate hydrochloride, 9.78 g dicyclohexylcarbodiimide and 6.12 g diisopropylethylamine were reacted together in 50 mL dichloromethane at 0°. 5.51 g 2-oxopentanoic acid in 10 mL dichloromethane was added dropwise at 0°. The pH of the reaction was adjusted to between 8 and 9 with diisopropylethylamine. The reaction mixture was stirred for four hours at 0°, then room temperature overnight. The next day, the reaction mixture was filtered, concentrated to dryness, and partitioned between ethyl acetate and water. The organic layer was washed with 5% sodium bisulfate, 5% sodium bicarbonate, and saturated sodium chloride solutions, and dried with magnesium sulfate. The organic layer was concentrated to give a yellow oil. The oil was then passed through a silica gel column and eluted with ethyl acetate/hexane (4:6) and ethyl acetate/hexane (1:1). Benzyl N-(2-oxopentanoyl)prolinate, [α]D25 -56.9, was isolated.

Provenance & Evidence