Reaction #2286343

Reaction equation

sodium nitrite

6-(4-amino-2,6-dichloro-phenylsulfanyl)-4-isopropyl-2H-pyridazin-3-one

6-(4-Amino-2,6-dichloro-phenylsulfanyl)-4-isopropyl-2H-pyridazin-3-one

cyanoacetylurethane

pyridine

→

(2-cyano-2-{[3,5-dichloro-4-(5-isopropyl-6-oxo-1,6-dihydro-pyridazin-3-ylsulfanyl)-phenyl]hydrazono}-acetyl)-carbamic acid ethyl ester

Yield 58.0%

(2-Cyano-2-{[3,5-dichloro-4-(5-isopropyl-6-oxo-1,6-dihydro-pyridazin-3-ylsulfanyl)-phenyl]-hydrazono}-acetyl)-carbamic acid ethyl ester

Yield 58.0%

Solvents

water

water

water

hydrochloric acid

water

Conditions

Workup

1. 1
   Washrinse (1.0 mL) of the Pasteur pipette
2. 2
   workup.ADDITIONMore concentrated hydrochloric acid (7.0 mL) was added
3. 3
   workup.STIRRINGThe reaction was stirred at 0° C. for an additional 1.3 h
4. 4
   OtherThe solids were removed by filtration
5. 5
   Filtrationthrough filter paper
6. 6
   Washwere rinsed with water
7. 7
   Temperaturecooled to 0° C
8. 8
   workup.ADDITIONUpon mixing
9. 9
   Otherorange-red solids immediately formed
10. 10
    workup.STIRRINGThis mixture was stirred at 0° C. for 1 h
11. 11
    FiltrationAt this time, the solids were collected by filtration
12. 12
    Filtrationthrough filter paper
13. 13
    WashThe solids were washed with water
14. 14
    Otherair-dried under house vacuum for 2 h
15. 15
    Otherdried under vacuum

Procedure

A mixture of 6-(4-amino-2,6-dichloro-phenylsulfanyl)-4-isopropyl-2H-pyridazin-3-one (85) (3.40 g, 10.4 mmol) in water (135 mL) and concentrated hydrochloric acid (68 mL) cooled to 0° C. was treated with a solution of sodium nitrite (853 mg, 12.36 mmol) in water (7.0 mL) via Pasteur pipette under the surface of the reaction mixture. This was followed by a water rinse (1.0 mL) of the Pasteur pipette. The resulting yellow mixture was stirred at 0° C. for 30 min. More concentrated hydrochloric acid (7.0 mL) was added. The reaction was stirred at 0° C. for an additional 1.3 h. The solids were removed by filtration through filter paper and were rinsed with water. The clear, yellow diazonium salt solution of the filtrate was quickly poured into a solution of cyanoacetylurethane (1.77 g, 11.33 mmol), pyridine (75 mL) and water (204 mL) cooled to 0° C. Upon mixing, orange-red solids immediately formed. This mixture was stirred at 0° C. for 1 h. At this time, the solids were collected by filtration through filter paper. The solids were washed with water, air-dried under house vacuum for 2 h, and then dried under vacuum to afford (2-cyano-2-{[3,5-dichloro-4-(5-isopropyl-6-oxo-1,6-dihydro-pyridazin-3-ylsulfanyl)-phenyl]hydrazono}-acetyl)-carbamic acid ethyl ester (86) (2.98 g, 58%) as an orange solid; ES(+)-HRMS m/e calcd for C19H18Cl2N6O4S (M+H)+ 497.0560, found 497.0559. Exact Mass=496.0487; Molecular weight=497.36

Source