反应详情

To a stirred solution of 4.31 g (0.022 mol) of 6-ethoxycarbonyl-2-pyridinecarboxylic acid in 100 ml of anhydrous pyridine, there are added 5.5 g (0.022 mol) of L-alanyl-L-proline ethyl ester hydrochloride and 4.6 g of N,N'-dicyclohexyl carbodiimide. Stirring is continued for 20 minutes at room temperature, and the bulky precipitate of dicyclohexyl urea is filtered and washed with acetone. The solvent from the filtrate and washings is distilled off under reduced pressure and the crude product obtained is purified by column chromatography over silica gel using chloroform:acetone (10:1) as eluant. The isolated solid is crystallized from an acetone/isopropyl ether/petroleum ether mixture, to give 4.27 g of the desired product as acicular crystals (yield: 53%).

1. filtrationthe bulky precipitate of dicyclohexyl urea is filtered
2. washwashed with acetone
3. distillationThe solvent from the filtrate and washings is distilled off under reduced pressure
4. customthe crude product obtained
5. customis purified by column chromatography over silica gel
6. customThe isolated solid is crystallized from an acetone/isopropyl ether/petroleum ether mixture