2-acetamido-3-sulfanylpropanoic acid

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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). 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 the organic layer was washed with brine dried on anhydrous MgSO4 filtered the solvent evaporated The crude intermediate 4 was treated with a solution of TFA (40%) in CH2Cl2 After 2 h the solvent was removed

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Cobalt chloride hexahydrate (CoCl2-6H2O (mw=237.9 g/mol, available from Acros)) and NAC (N-Acetyl-L-Cysteine, HSCH2CH(NHCOCH3)CO2H (mw=163.19 g/mol, available from Sigma)) was dissolved in water, resulting in the formation of cobalt-dichloride-N-acetyl cysteine (CoCl2—NAC), referred to herein as the Co—NAC contrast agent. All chemicals were purchased from commercial sources and were used without any further purification. For toxicity testing, two different Co—NAC solutions with low (1 wt. %) concentration of cobalt chloride and with high (10%) concentration were prepared. In both cases, the concentration of NAC in the solution was 2 wt. %. The Co—NAC solution with low cobalt chloride concentration was prepared by dissolving 100 mg (0.42 mmol) of CoCl2-6H2O and 200 mg (1.22 mmol) of NAC in 9.7 mL distillated water. The solution with high cobalt chloride concentration was prepared by dissolving 1000 mg (4.2 mmol) of CoCl2-6H2O and 200 mg (1.22 mmol) of NAC in 8.8 mL distilled water. In both cases, the solutions were sonicated at the room temperature for 15 minutes to completely dissolve the components. To avoid any contaminations and bacteria grow, the fresh Co—NAC solutions were prepared every morning for 6 days and immediately delivered for toxicity testing (see, Example 2 below).

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Cobalt chloride hexahydrate (CoCl2-6H2O (mw=237.9 g/mol, available from Acros)) and NAC (N-Acetyl-L-Cysteine, HSCH2CH(NHCOCH3)CO2H (mw=163.19 g/mol, available from Sigma)) was dissolved in water, resulting in the formation of cobalt-dichloride-N-acetyl cysteine (CoCl2—NAC), referred to herein as the Co—NAC contrast agent. All chemicals were purchased from commercial sources and were used without any further purification. For toxicity testing, two different Co—NAC solutions with low (1 wt. %) concentration of cobalt chloride and with high (10%) concentration were prepared. In both cases, the concentration of NAC in the solution was 2 wt. %. The Co—NAC solution with low cobalt chloride concentration was prepared by dissolving 100 mg (0.42 mmol) of CoCl2-6H2O and 200 mg (1.22 mmol) of NAC in 9.7 mL distillated water. The solution with high cobalt chloride concentration was prepared by dissolving 1000 mg (4.2 mmol) of CoCl2-6H2O and 200 mg (1.22 mmol) of NAC in 8.8 mL distilled water. In both cases, the solutions were sonicated at the room temperature for 15 minutes to completely dissolve the components. To avoid any contaminations and bacteria grow, the fresh Co—NAC solutions were prepared every morning for 6 days and immediately delivered for toxicity testing (see, Example 2 below).

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir: