反应详情

Acetylalanylalanylleucine (1.5 mmole) and N-methylmorpholine (3 mmole) are dissolved in methylene chloride (10 ml) and diluted with dry tetrahydrofuran (250 ml) and cooled to -20° to -25°. Isobutyl chloroformate (1.5 mmole) is added with stirring and the mixture is stirred for 10 minutes. A solution of 2-azaalanyl-dl-lactic acid ethyl ester (1.5 mmole, Example 5, Step A) in tetrahydrofuran (3 ml) is added and the mixture is allowed to warm to room temperature over a period of 2 hours and stirred overnight. The precipitate is filtered off and the filtrate is evaporated to dryness. Chromatography on silica gel (25 gm) and elution with 12% methanol in chloroform gives acetylalanylalanylleucyl-2-azaalanyl-dl-lactic acid ethyl ester.

1. temperaturecooled to -20° to -25°
2. stirringthe mixture is stirred for 10 minutes
3. stirringstirred overnight
4. filtrationThe precipitate is filtered off
5. customthe filtrate is evaporated to dryness
6. washChromatography on silica gel (25 gm) and elution with 12% methanol in chloroform