4-Methylmorpholine → Acetylalanylalanylleucyl-2-azaalanyl-DL-lactic acid ethyl ester

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Reaction Steps

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.

Provenance & Evidence