Pyridinium chloride → 2-Amino-5-nitropyridin-3-ol

Temperature

150 °C

Into a 500 mL round bottom flask were combined 2-amino-3-methoxy-5-nitropyridine (0.300 g, 0.00177 mol) and solid pyridine hydrochloride (8.8 g, 0.076 mol). The solid mixture was heated at 150° C. upon which the solids fused (the evolution of a gas was also apparent). The mixture was held at 150° C. for three hours upon which reaction was deemed complete by LC-MS. After allowing to cool to 80° C., the mixture was poured on to ice and the aqueous layer was extracted with ethyl acetate (3×100 ml). The combined organic extracts were washed with water (2×100 mL), dried (Na2SO4), filtered and concentrated under vacuum to leave a crude residue. The residue was purified by column chromatography on silica gel using a methanol:methylene chloride (0-10%) gradient as eluent to give the product as a solid (0.138 g, 49%) which was used directly in the next step. LC-MS 1.28 min. m/z=155.9 (M+1).

1. customInto a 500 mL round bottom flask were combined
2. customThe mixture was held at 150° C. for three hours upon which reaction
3. temperatureto cool to 80° C.
4. additionthe mixture was poured on to ice
5. extractionthe aqueous layer was extracted with ethyl acetate (3×100 ml)
6. washThe combined organic extracts were washed with water (2×100 mL)
7. dry with materialdried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated under vacuum
10. customto leave a crude residue
11. customThe residue was purified by column chromatography on silica gel using a methanol

ORD record

ord-263baf0fabe041d0bdcb25d414b56247

Source dataset

uspto-grants-2007_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07312233B2