p-Toluenesulfonic acid → 4,5-Dichloro-2-(tetrahydro-pyran-2-yl)-2H-pyridazin-3-one

HRID 69326Notes

Reaction equation

HRID 69326 reaction equation
[Cl:1][C:2]1[C:7]([Cl:8])=[CH:6][N:5]=[N:4][C:3]=1[OH:9].[O:10]1[CH:15]=[CH:14][CH2:13][CH2:12][CH2:11]1.C1(C)C=CC(S(O)(=O)=O)=CC=1>O1CCCC1>[Cl:1][C:2]1[C:3](=[O:9])[N:4]([CH:11]2[CH2:12][CH2:13][CH2:14][CH2:15][O:10]2)[N:5]=[CH:6][C:7]=1[Cl:8]

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 80803,4-dihydro-2H-pyranHCID 178518919HCID 178518919, compound

Product 1

HCID 107292624,5-Dichloro-2-(tetrahydro-pyran-2-yl)-2H-pyridazin-3-one

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A mixture of 4,5-dichloropyridazin-3-ol (42 g, 250 mmol), 3,4-dihydro-2H-pyran (168 g, 2.00 mol) and p-toluenesulfonic acid (8.8 g, 51 mmol) in tetrahydrofuran (2 L) was heated at reflux for 2 days. After cooling to room temperature, the reaction mixture was concentrated in vacuo and purified by silica gel chromatography (Gradient: 3% to 5% ethyl acetate in petroleum ether). The product was obtained as a white solid. Yield: 42 g, 170 mmol, 68%. 1H NMR (400 MHz, CDCl3) δ 7.84 (s, 1H), 6.01 (br d, J=11 Hz, 1H), 4.10-4.16 (m, 1H), 3.70-3.79 (m, 1H), 1.99-2.19 (m, 2H), 1.50-1.80 (m, 4H).

Workup

  1. temperaturewas heated
  2. temperatureat reflux for 2 days
  3. concentrationthe reaction mixture was concentrated in vacuo
  4. custompurified by silica gel chromatography (Gradient: 3% to 5% ethyl acetate in petroleum ether)
  5. customThe product was obtained as a white solid

Sources & evidence

ORD record
ord-851d5cdd4705473ba1cf9ce8c50755ec
Source dataset
uspto-grants-2014_09
Patent number
US08822494B2

Reaction notes

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