Hydrogen Bromide → (2-Amino-3-phenylpropyl)phosphonic acid

Participants

Reaction Steps

A mixture of [2-[[(4-methylphenyl)sulfonyl]amino]-3-phenylpropyl]phosphonic acid, diethyl ester (5.9 g., 13.9 mmole), phenol (8.0 g., 85.1 mmole), and 48% aqueous hydrobromic acid (50 ml.) was refluxed for 5.5 hours. The cooled mixture was diluted with water (50 ml.) and washed with ethyl acetate (2×50 ml.). The aqueous phase was evaporated to dryness, taken up in water (30 ml.) and evaporated again. This was repeated twice more. Finally, the residue was taken up in water and applied to an AG50W-X2 (H+ form) column (60 ml. bed volume) and eluted first with water then with 5% pyridine-water. The fractions containing the desired product were combined and evaporated to dryness. The solid residue was triturated with acetonitrile to give 2.55 g of (2-amino-3-phenylpropyl)phosphonic acid as an off-white crystalline solid; m.p. 347° (dec.); Rf (isopropanol/conc. NH4OH/water; 7:2:1)=0.27.

Provenance & Evidence