Réaction #2013602

Équation de réaction

2-amino-4,5-difluoro-1,3-benzothiazole

HCl

NaNO2

HCl

→

title compound

2-Chloro-4,5-difluoro-1,3-benzothiazole

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGstirring
2. 2
   workup.WAITwas continued at ambient temp. for 30 min
3. 3
   ExtractionThe reaction mixture was extracted with diethyl ether (3×30 mL)
4. 4
   LavageThe combined organic layers were washed with water (10 mL), dilute ammonium hydroxide (10 mL), brine (20 ml)
5. 5
   Séchagedried over anhydrous Na2SO4
6. 6
   Filtrationfiltered
7. 7
   Concentrationconcentrated under reduced pressure
8. 8
   AutreThe residue was purified by column chromatography on silica gel (eluted by 2% methanol in methylene chloride)

Mode opératoire

To a mixture of 2-amino-4,5-difluoro-1,3-benzothiazole (130 mg, 0.70 mmol) and CuSO4 (20 mg) in conc. HCl (20 mL) was added NaNO2 (96 mg, 1.4 mmol, 2 eq, dissolved in 5 mL of water) dropwise at −10° C. over about 15 min. The reaction mixture was stirred for 1 h, poured into a solution of CuCl (67 mg, 0.7 mmol, 1 eq.) in conc. HCl (20 mL), and stirring was continued at ambient temp. for 30 min. The reaction mixture was extracted with diethyl ether (3×30 mL). The combined organic layers were washed with water (10 mL), dilute ammonium hydroxide (10 mL), brine (20 ml), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel (eluted by 2% methanol in methylene chloride) to afford the title compound. 1H-NMR (CDCl3, 300 MHz): δ=7.20-7.15 (m, 1H), 7.13-7.04 (m, 1H).

Source