(S)-4-Nitrophenyl 2-(((benzyloxy)carbonyl)amino)-4-methylpentanoate → Z-Leu-Asn-Asn-Phe-NHNH-BOC

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Reaction Steps

26.5 g of H-Asn-Asn-Phe-NHNH-BOC are dissolved in 58 ml of warm dimethylformamide, a solution of 24.2 g of Z-Leu-ONP in 16 ml of dimethylformamide is added at room temperature, and the mixture is stirred until it solidifies. After standing overnight the mixture is triturated with ether, filtered off, dissolved in 190 ml of dimethylformamide, and the product reprecipitated by adding dropwise to 1.5 liters of ether. The product is filtered off and washed with ether until free of nitrophenol. Rf = 0.45 in the system chloroform-methanol (7:3) on silica gel.

Provenance & Evidence