Stannous Chloride → 5-Amino-2,3-dichloropyridine

Anhydrous SnCl2 (300 g, 1.58 mol) and concentrated HCl (350 mL) were charged to a 5 L flask with mechanical stirrer and thermocouple. The flask was cooled in ice and the product of Example 2B (100 g, 0.518 mol) was added in portions maintaining the temperature below 65° C. After the addition was complete, the cold bath was removed, and the mixture was stirred for 2 hours at ambient temperature. The mixture was cooled in ice as 25% aqueous NaOH (1000 mL) was added to bring the mixture to pH>10. The mixture was extracted with CH2Cl2 (1×600 mL, 2×400 mL) and the combined extracts were washed with brine (200 mL), dried (MgSO4), and concentrated under vacuum. The residual solid was crystallized from a mixture of water (500 mL) and ethanol (100 mL) to provide the title compound as a solid. 1H NMR (CDCl3, 300 MHz) δ 3.80 (br s, 2H), 7.10 (d, J=3 Hz, 1H), 7.77 (d, J=3 Hz, 1H); MS (DCI/NH3) m/z 180/182/184 (M+NH4)+ 163/165/167 (M+H)+.

1. temperatureThe flask was cooled in ice
2. temperaturemaintaining the temperature below 65° C
3. additionAfter the addition
4. customthe cold bath was removed
5. temperatureThe mixture was cooled in ice as 25% aqueous NaOH (1000 mL)
6. additionwas added
7. extractionThe mixture was extracted with CH2Cl2 (1×600 mL, 2×400 mL)
8. washthe combined extracts were washed with brine (200 mL)
9. dry with materialdried (MgSO4)
10. concentrationconcentrated under vacuum
11. customThe residual solid was crystallized from a mixture of water (500 mL) and ethanol (100 mL)

ORD record

ord-99c2f641fed74c9ca43d96b78aae9546

Source dataset

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07354937B2