Hydrochloric Acid → 2,4-Dichlorobenzothiazole

Temperature

65 °C

Anhydrous CuCl2 (Aldrich, 4.37 g, 32.5 mmol), t-butyl nitrite (Aldrich, 4.83 mL, 40.6 mmol) and anhydrous acetonitrile (EM, 50 mL) were added to a 3-necked round-bottomed flask equipped with a reflux condenser, an additional funnel and a gas outlet tube. The mixture was warmed to 65° C. and a suspension of 2-amino-4-chlorobenzothiazole in 50 mL of acetonitrile. During the addition, the reaction mixture tuned to black and gas evolved. After gas evolution is complete, the reaction was allowed to reach room temperature. The reaction mixture was poured to 300 mL of 20% aqueous HCl, extracted 3× with EtOAc (400 mL). The organic layers were washed twice with a brine solution (300 mL), dried over Na2SO4 and concentrated. The residue was purified by chromatography with 60% CH2Cl2/hexanes to give 4.8 g of product. 1H NMR (400 MHz, DMSO-d6) δ 8.10 (dd, J=8.1, 1.0 Hz, 1H), 7.68 (dd, J=7.9, 1.0 Hz, 1H), 7.51 (t, J=8.0 Hz, 1H).

1. customequipped with a reflux condenser, an additional funnel and a gas outlet tube
2. additionDuring the addition
3. customto reach room temperature
4. extractionextracted 3× with EtOAc (400 mL)
5. washThe organic layers were washed twice with a brine solution (300 mL)
6. dry with materialdried over Na2SO4
7. concentrationconcentrated
8. customThe residue was purified by chromatography with 60% CH2Cl2/hexanes

ORD record

ord-cc4ecd6cf4f14adbae0b1dad2c6b7006

Source dataset

uspto-grants-2011_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07960408B2