Chloroform → Ethyl N-(1-((benzyloxy)carbonyl)-L-prolyl)-L-leucinate

Participants

Reaction Steps

N-Benzyloxycarbonyl-L-proline (1.25 g) and L-leucine ethyl ester hydrochloride (1.0 g) are suspended into chloroform (10 ml), and therein is dissolved triethylamine (1.4 ml). To the solution is added ethyl 2-(p-toluenesulfonyloxyimino)-2-cyanoacetate (1.5 g) and the mixture is stirred at room temperature for 16 hours. After reaction, the reaction mixture is extracted with ethyl acetate. The exatract is washed with water, 1 N aqueous sodium hydrogen carbonate, water, 1 N hydrochloric acid and water in order and then dried over anhydrous magnesium sulfate. After drying, the solvent is distilled off and the residual oily substance (1.6 g) is dissolved in chloroform and then the mixture is subjected to a silica gel column chromatography (developer: chloroform). The first fraction thus obtained is concentrated and the resulting residue is crystallized from ether-petroleum ether to give N-(N-benzyloxycarbonyl-L-prolyl)-L-leucine ethyl ester (80 mg), melting point: 60°-64° C. The product is identified with an authentic sample by infrared spectrum.

Provenance & Evidence