Water → 4-Bromo-6-chloro-2,3-dihydropyridazin-3-one

HRID 594048Notes

Reaction equation

HRID 594048 reaction equation
N([O-])=O.[Na+].OS(O)(=O)=O.[Br:10][C:11]1[CH:16]=[C:15]([Cl:17])[N:14]=[N:13][C:12]=1N.[OH2:19]>C(O)(=O)C>[Br:10][C:11]1[C:12](=[O:19])[NH:13][N:14]=[C:15]([Cl:17])[CH:16]=1

Participants

6

Reactant 4

HCID 962WaterHCID 1118Sulfuric AcidHCID 220244193-Amino-4-bromo-6-chloropyridazineHCID 23668193Sodium Nitrite

Product 1

HCID 115865224-Bromo-6-chloro-2,3-dihydropyridazin-3-oneYield 83%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Conditions

Temperature
0 °C

Procedure

To a cooled solution (0-5° C.) of NaNO2 (2.4 equiv.) in H2SO4 conc. (23 equiv.) was added 4-bromo-6-chloropyridazin-3-amine (1.0 equiv.) in acetic acid (0.25 M). The reaction mixture was stirred at 0° C. for 30 min before warming to room temperature and stirring for 1 hour. Water was added and stirred at room temperature for a further 4 hours. The reaction mixture was then extracted with ethyl acetate, dried over MgSO4 and concentrated in vacuo to yield a brown oil. The oil was further purified by silica gel column chromatography eluting with 100% heptanes to 80% ethyl acetate/heptanes to yield 4-bromo-6-chloropyridazin-3(2H)-one as an off-white solid in 83% yield. LCMS (m/z) (M+H)=208.9/210.9, Rt=0.42 min. 1H NMR (400 MHz, <dmso>) δ ppm 8.08-8.32 (m, 1H) 13.25-13.71 (m, 1H).

Workup

  1. temperaturebefore warming to room temperature
  2. stirringstirring for 1 hour
  3. stirringstirred at room temperature for a further 4 hours
  4. extractionThe reaction mixture was then extracted with ethyl acetate
  5. dry with materialdried over MgSO4
  6. concentrationconcentrated in vacuo
  7. customto yield a brown oil
  8. customThe oil was further purified by silica gel column chromatography
  9. washeluting with 100% heptanes to 80% ethyl acetate/heptanes

Sources & evidence

ORD record
ord-9657687f038d4bbcb51a286368440769
Source dataset
uspto-grants-2016_01
Patent number
US09242969B2

Reaction notes

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