Dicyclohexylcarbodiimide → N-tert-butyloxycarbonyl-S-p-methoxybenzyl-D-cysteinyl-L-proline tert-butyl ester

Participants

Reaction Steps

To a solution of L-proline tert-butyl ester (0.85 g) and hydroxybenzotriazole (0.67 g) in methylene chloride (10 ml) chilled in an ice bath, dicyclohexylcarbodiimide (1.03 g) and N-tert-butyloxycarbonyl-S-p-methoxybenzyl-D-cysteine (1.7 g) are added in that order. After fifteen minutes, the ice bath is removed and the mixture is stirred at room temperature overnight. The precipitate is filtered off and the filtrate is washed with 10% potassium bisulfate, water, saturated sodium bicarbonate, and water. The organic phase is dried and concentrated to dryness in vacuo to give N-tert-butyloxycarbonyl-S-p-methoxybenzyl-D-cysteinyl-L-proline tert-butyl ester as an oil. Rf =0.2 (silica gel, chloroform).

Provenance & Evidence