N-Acetyl-DL-cysteine → 5-(2-Acetylamino-3-mercapto-propionylamino)-2-hydroxy-benzoic acid

Participants

Reaction Conditions

Reaction Steps

To the solution of 2-acetylamino-3-mercapto-propionic acid (3.0 mmol) in 50 mL of dimethylformamide, hydroxybenzotriazole (3.3 mmol) and DCC (3.3 mmol) were added with stirring at 0° C. for 1 h. To the reaction mixture, 4 or 5-amino-2-tert-butoxy-benzoic acid tert-butyl ester (3) (3.0 mmol) was added and stirred mechanically for 3 h at 0° C. and 72 h at room temperature. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent. The oily residue thus obtained was dissolved in ethyl acetate; the organic layer was washed with brine, dried on anhydrous MgSO4, filtered and the solvent evaporated. The crude intermediate 4 was treated with a solution of TFA (40%) in CH2Cl2. After 2 h the solvent was removed to obtain compound (5) as a crude residue. The residue was loaded on a silica gel open column and eluted with CH2Cl2/MeOH (8/2), from which 4 or 5-(2-Acetylamino-3-mercapto-propionylamino)-2-hydroxy-benzoic acid (5), compound of Formula XI, was obtained (78% yield).

Provenance & Evidence