Dicyclohexylcarbodiimide → N-[3-(ethoxycarbonyl)-2-(2-methylpropyl)butanoyl]-O-methyl-L-tyrosine N-methylamide

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-(ethoxycarbonyl)-2-(2-methylpropyl)butanoic acid (7.5 g., 0.037 mol.) and dichloromethane (70 mls.) was stirred and cooled to 0° C. To the mixture was added dropwise a solution of N,N'-dicyclohexylcarbodiimide (7.6 g., 0.37 mol.) in dichloromethane (20 mls.) and the reaction mixture was allowed to warm to room temperature. A solution of O-methyl-L-tyrosine N-methylamide (7.7 g., 0.037 mol.) in dichloromethane (45 mls.) was added to the reaction mixture and the resulting mixture was stirred overnight at room temperature. A saturated sodium bicarbonate solution (100 mls.) was added to the reaction mixture and the resulting mixture was stirred for an additional hour. The reaction mixture was filtered and the organic layer recovered and then dried on anhydrous sodium sulfate. The solvent was removed by evaporation in vacuo to yield a sticky brown solid. The solid was purified by chromatography on normal phase silica eluting with 20% hexane in ethyl acetate to yield N-[3-(ethoxycarbonyl)-2-(2-methylpropyl)butanoyl]-O-methyl-L-tyrosine N-methylamide as a mixture of 4 diastereomers.

Provenance & Evidence