Triethylamine → N-benzyloxycarbonyl-L-prolyl-L-prolinal diethyl acetal

Participants

Reaction Steps

To a solution of L-prolinal diethyl acetal hydrochloride (898 mg) and benzyloxycarbonyl-L-proline (1.2 g, 4.82 mmol) in dichloromethane (15 ml) are added successively, under ice-cooling and agitation, 1-hydroxy-benzotriazole (645 mg), triethylamine (0.68 ml, 4.88 mmol) and N,N-dicyclohexylcarbodiimide (1.0 g, 4.90 mmol). After the addition, stirring is further continued for 2 hours under ice-cooling, and then for 45 minutes at room temperature. Ether (40 ml) is added to the reaction mixture and the mixture is filtered for removal of insolubles. The filtrate is washed successively with water (10 ml), a saturated aqueous solution of sodium hydrogen carbonate (10 ml) and a saturated aqueous solution of edible salt (10 ml), dried over magnesium sulfate and filtered. The filtrate is concentrated to dryness under reduced pressure. The residue is purified by column chromatography on silica gel (benzene-ether-ethanol, 20:20:1) to give 1.125 g (69%) of the title compound as pale yellow crystals.

Provenance & Evidence