Sodium Hydroxide → O-Ethyl-L-tyrosine

Participants

Reaction Steps

N-tert-Butoxycarbonyl-O-ethyl-L-tyrosine (III, EXAMPLE 2, 195 g, 632 mmol) is suspended in THF (1200 mL), p-toluenesulfonic acid monohydrate (240 g, 1.26 mol) is added at 20-25°. The resulting mixture is heated at reflux for 2 hr. The mixture is neutralized with sodium hydroxide (2N, about 700 mL) to pH between 5 and 6 at 20-25°. The resulting mixture is stirred at 5° for 2 hr before it is filtered. The cake is washed with THF/water (4/1, 50 mL×3). The precipitate is dried to give the title compound. The filtrate is removed of all volatile, adjusted pH again to give more precipitate. The precipitate is dried to give additional title compound, NMR (D2O/NaOH) δ7.14, 6.88, 4.02, 3.40, 2.88, 2.73 and 1.30; CMR (D2O/NaOH) δ182.8, 157.0, 131.4, 131.0, 64.8, 57.8, 40.3 and 14.3.

Provenance & Evidence