Diisopropylethylamine → N-[[1-(2-azidoethyl)cyclopentyl]carbonyl]-4nitro-L-phenylalanine methyl ester

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Reaction Steps

A solution of 4-nitro-L-phenylalanine methyl ester hydrochloride (3.0 g, 11.5 mmol), 1-(2-azidoethyl)cyclopentane carboxylic acid (2.3 g, 12.7 mmol) and BOP (5.34 g, 12.1 mmol) in dichloromethane (6 mL) and DMF (4 mL) was treated with diisopropylethylamine (4.2 mL, 24.2 mmol). The mixture was stirred overnight at which time TLC (1:1 hexane:ethyl acetate) indicated no more starting material. The mixture was diluted with water, extracted with ethyl acetate. The extracts were washed with water and brine, then were dried (Na2SO4), filtered and evaporated in vacuo. The residue was purified by chromatography over silica gel (3:1hexane:ethyl acetate) to afford 4.26 g of N-[[1-(2-azidoethyl)cyclopentyl]carbonyl]-4-nitro-L-phenylalanine methyl ester.

Provenance & Evidence