Lithium Hexamethyldisilazide → 5-Chloro-3-(2-fluoro-4-trimethylsilanyl-phenylamino)-pyrazine-2-carboxylic acid

Temperature

-78 °C

To a solution of 2-fluoro-4-trimethylsilanyl-phenylamine (3.8 g, 20.7 mmol, 2.0 eq) in anhydrous THF (150 mL) at −78° C. under N2 was added dropwise a solution of 1.0 M LHMDS in THF (33.2 mL, 30 mmol, 3.2 eq) over 20 minutes. After 1 hour at −78° C., a solution of 3,5-dichloro-pyrazine-2-carboxylic-acid (2.0 g, 10.3 mmol) in anhydrous THF (30 mL) was added. The mixture was stirred at −78° C. for 30 minutes, and then stirred at ambient temperature for 18 hours. The mixture was quenched with water and the pH adjusted to pH 2 by the addition of 2 N HCl. The reaction mixture was extracted with ethyl acetate, and the organic layer washed with water and brine, then dried (Na2SO4), filtered and evaporated in vacuo. The resultant residue was purified by column chromotagraphy (Si-PPC, gradient 20 to 50% ethyl acetate in hexane, followed by 0% to 30%, methanol in dichloromethane) to give the desired compound as a yellow solid (2.95 g, 83.8%). 1H NMR (CDCl3, 400 MHz) δ ppm 10.41 (s, 1H), 8.28 (t, J=7.79 Hz, 1H), 7.93 (s, 1H), 7.40-7.23 (m, 2H), 0.27 (s, 9H).

1. stirringstirred at ambient temperature for 18 hours
2. customThe mixture was quenched with water
3. additionthe pH adjusted to pH 2 by the addition of 2 N HCl
4. extractionThe reaction mixture was extracted with ethyl acetate
5. washthe organic layer washed with water and brine
6. dry with materialdried (Na2SO4)
7. filtrationfiltered
8. customevaporated in vacuo
9. customThe resultant residue was purified by column chromotagraphy (Si-PPC, gradient 20 to 50% ethyl acetate in hexane, followed by 0% to 30%, methanol in dichloromethane)

ORD record

ord-cfdc63f6aaf345319e313daf5ff7834d

Source dataset

uspto-grants-2012_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08288408B2