4-Nitrophenol → Boc-Phe-ONp

Participants

Reaction Steps

To a solution of N-tert-butoxycarbonylphenylalanine (53 g, 0.2 mol) and p-nitrophenol (27.8 g, 0.2 mol) in ethyl acetate (200 ml) in an ice-water bath was dropwise added a solution of N,N'-dicyclohexylcarbodiimide (41.2 g, 0.2 mol) in ethyl acetate (100 ml), and the mixture was stirred in an ice-water bath for 3 hours and then at room temperature for 20 hours. The precipitated N,N'-dicyclohexylcarbodiurea was filtered off and the filtrate was concentrated under reduced pressure. The residue thus obtained was recrystallized from ethyl acetate-hexane to give N-tert-butoxycarbonylphenylalanine p-nitrophenyl ester [61.7 g, 80% (% by weight, hereinafter the same)].

Provenance & Evidence