Urea → Ethyl 4-((4-((2-chloro-4-nitrophenyl)diazenyl)phenyl)(3-hydroxypropyl)amino)butanoate

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Reaction Steps

2-Chloro-4-nitroaniline 2.5 g (10 mmol) is placed into a 125 mL flask and 6 mL of water is added. Agitation and sonication partially dissolves the yellow chloronitroaniline. Then the stirred solution is cooled with ice in a fume hood and 15.8 mL of concentrated (˜12 M) HCl is added. Most of the yellow material dissolves at this point. The flask is fitted with a dropping funnel, and a solution of 1.51 g (21.9 mmol) sodium nitrite in 3-4 mL of water is added to the dropping funnel and slowly added to the solution in the flask with stirring, over about 20 minutes. When this is complete, 0.6 g (˜21 mmol) of urea is added followed by 2.73 g of ethyl 4-[(3-hydroxypropyl)phenylamino]butanoate as a solution in 8.2 mL acetic acid. After a minute 20 g of sodium acetate in 50 mL of water is added. The mixture is allowed to stir for an hour at room temperature. Most of the product is separated as an emulsion. The mixture is partitioned between ethyl acetate and water. The organic layer is washed with NaHCO3 (3×50 ml), brine and dried over anhydrous sodium sulfate. Then the organic solvents are evaporated to a syrup. The crude product is chromatographed on silica gel (1.5×20 inches) eluting with 50% ethyl acetate/hexane. The appropriate fractions are collected, combined, evaporated (30-40 degrees), and dried in a vacuum. The product is a dark oil. The yield is approximately 68-70%.1H NMR (DMSO-d6) δ: 8.42 (d, J=2.5 Hz, aromatic proton, 1H), 8.24 (dd, J1=9 Hz, J2=2.5 Hz, aromatic proton, 1H), 7.86 (d, J=9 Hz, 2H), 7.77 (d, J=9 Hz, 1H), 6.92 (d, J=9 Hz, aromatic protons, 2H), 4.67 (t, J=6 Hz, OH, 1H), 4.07 (q, J=7 Hz, CH2O, 2H), 3.5 (m, aliphatic protons, 6H), 2.40 (t, J=7 Hz, aliphatic protons, 2H), 1.84 (m, aliphatic protons, 2H), 1.72 (m, aliphatic protons, 2H), 1.18 (t, J=7 Hz, CH3, 3H).

Provenance & Evidence