L-Hydroxyproline → trans-4-Hydroxy-1-(4-nitrobenzyloxycarbonyl)-L-proline

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Reaction Steps

6.55 g of trans-4-hydroxyl-L-proline and 7.5 ml of triethylamine were dissolved in 15 ml of water, and a solution of 15.95 g of S-p-nitrobenzyloxycarbonyl-4,6-dimethyl-2-mercaptopyrimidine in 35 ml of dioxane was added thereto dropwise. The resulting mixture was stirred at room temperature for 1.5 hours and allowed to stand overnight. To the reaction mixture was added 30 ml of a 2N sodium hydroxide aqueous solution under ice-cooling, and the resulting mixture was extracted with diethyl ether. The ethereal layer was washed with 20 ml of a 1N sodium hydroxide aqueous solution and combined with the alkaline aqueous layer. The combined mixture was made acidic with 100 ml of a 2N hydrochloric acid aqueous solution and extracted with ethyl acetate. The ethyl acetate layer was washed with a 2N aqueous solution of hydrochloric acid, dried over sodium sulfate and distilled off to remove the solvent. The resulting crude crystals were washed with warm ethyl acetate to obtain trans-1-(p-nitrobenzyloxycarbonyl)-4-hydroxy-L-proline.

Provenance & Evidence