Ethylmorpholine → N-[(1,1-Dimethylethoxy)carbonyl]-L-alanyl-L-proline phenylmethyl ester

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Reaction Steps

A mixture of 6.0 g (0.025 m) of the benzyl ester of L-proline, 4.7 g (0.025 m) of N-tert.-butoxycarbonyl-L-alanine, 6.75 g (0.05 m) of 1-hydroxybenzotriazole, 3.2 ml (2.82 g, 0.025 m) of N-ethylmorpholine and 65 ml of dry tetrahydrofuran was cooled, filtered and added to a mixture of 5.15 g (0.025 m) of dicyclohexylcarbodiimide and 10 ml of tetrahydrofuran. The mixture was stirred at 0° for 30 minutes, then, at 25° for 18 hours. The reaction mixture was filtered. The filtrate was evaporated to give a residue which was dissolved in ethyl acetate. The solution was washed with 1 to 10% acetic acid, water, 5% sodium bicarbonate solution and brine, then, dried over anhydrous magnesium sulfate and concentrated to leave 9.8 g of crude N-tert.-butoxycarbonyl-L-alanyl-L-proline, benzyl ester (the t-boc).

Provenance & Evidence