Sodium borohydride → 3-Amino-4-{[5-(5-chloro-thiophen-2-yl)-isoxazol-3-ylmethyl]-amino}-benzoic acid methyl ester

Participants

Reaction Steps

97.1 mg (0.41 mmol) NiCl2.6H2O were dissolved in 10 mL MeOH and treated under ultrasonic conditions. 46.4 mg (1.24 mmol) NaBH4 were added. After 15 minutes a solution of 214.0 mg (0.54 mmol) 4-{[5-(5-Chloro-thiophen-2-yl)-isoxazol-3-ylmethyl]-amino}-3-nitro-benzoic acid methyl ester in 20 mL CH2Cl2 was added. After further 15 minutes 55.6 mg (1.48 mmol) NaBH4 were added in three portions. The reaction mixture was treated under ultrasonic conditions for 2 h. Addition of NaBH4 (55.6 mg each time) and treatment under ultrasonic conditions had to be repeated three times to achieve complete conversion. The reaction mixture was filtered over “Celite” and the filtrate was concentrated under reduced pressure. The residue was suspended in 30 mL MeOH. After filtration the filtrate was concentrated under vacuo and the residue was taken up in 100 mL CH2Cl2. The organic layer was washed four times with water, dried over anhydrous MgSO4 and concentrated under reduced pressure to afford crude 3-Amino-4-{[5-(5-chloro-thiophen-2-yl)-isoxazol-3-ylmethyl]-amino}-benzoic acid methyl ester as a brown oil.

Provenance & Evidence