反应详情

A suspension of 2-Amino-3-nitro-5-pyridin-3-yl-benzoic acid methyl ester (0.92 g, 3.37 mmol) in aqueous sulfuric acid (50% v/v, 9 ml) was stirred at ambient temperature for 1 h before being cooled in an ice bath and treated over 5 min with an aqueous sodium nitrite solution (20% w/v, 1.4 ml). The mixture was stirred in the cold for 1.5 h before being treated with a solution of potassium thiocyanate (0.42 g) in water (1.0 ml) in one portion. The resultant mixture was stirred in the cold for 15 min and then added to a suspension of copper (I) thiocyanate (0.71 g) in water (2.8 ml) whilst cooling in an ice-bath. The mixture was stirred in the cold for 2 h and then heated to 70° C. for 20 min. After cooling to ambient temperature, the mixture was poured into a saturated aqueous solution of sodium hydrogen carbonate (200 ml) and extracted with ethyl acetate (3×100 ml) which was washed with brine (200 ml) and dried (MgSO4). The solvent was removed in vacuo to give a residue which was purified by flash chromatography (silica) eluting with 80% to 100% ethyl acetate in 40-60 petroleum ether. The 3-Nitro-5-pyridin-3-yl-2-thiocyanato-benzoic acid methyl ester was obtained as a pale yellow solid (0.78 g, 74%).

1. temperaturebefore being cooled in an ice bath
2. stirringThe mixture was stirred in the cold for 1.5 h
3. temperaturewhilst cooling in an ice-bath
4. stirringThe mixture was stirred in the cold for 2 h
5. temperatureheated to 70° C. for 20 min
6. temperatureAfter cooling to ambient temperature
7. extractionextracted with ethyl acetate (3×100 ml) which
8. washwas washed with brine (200 ml)
9. dry with materialdried (MgSO4)
10. customThe solvent was removed in vacuo
11. customto give a residue which
12. customwas purified by flash chromatography (silica)
13. washeluting with 80% to 100% ethyl acetate in 40-60 petroleum ether