Reaction #2286283

Reaction equation

methanol

[4-(6-chloro-5-isopropyl-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid

[4-(6-Chloro-5-isopropyl-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid

sodium acetate

→

[4-(5-isopropyl-6-oxo-1,6-dihydro-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid

Yield 65.0%

[4-(5-Isopropyl-6-oxo-1,6-dihydro-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid

Yield 65.0%

Solvents

methylene chloride

—

hexanes

ethyl acetate

acetic acid

Conditions

Workup

1. 1
   TemperatureAt this time, the reaction mixture was cooled to room temperature
2. 2
   Concentrationwas concentrated under vacuum
3. 3
   workup.ADDITIONThe resulting residue was diluted with water (100 mL)
4. 4
   workup.ADDITIONmade basic by the addition of a 1N aqueous sodium hydroxide solution
5. 5
   Extractionwas extracted with ethyl acetate (200 mL)
6. 6
   workup.ADDITIONThe water layer was acidified to pH=4 by the addition of a 1N aqueous hydrochloric acid solution
7. 7
   Extractionwas extracted with ethyl acetate (2×200 mL)
8. 8
   Washwashed with a saturated aqueous sodium chloride solution
9. 9
   Dryingdried with magnesium sulfate
10. 10
    Filtrationfiltered
11. 11
    Concentrationconcentrated under vacuum
12. 12
    Otherto afford a solid
13. 13
    Otherto form a solution and it
14. 14
    Otherwas absorbed onto silica
15. 15
    Concentrationconcentrated under vacuum
16. 16
    OtherThe preabsorbed solid was purified by column chromatography
17. 17
    Washeluted with 20% ethyl acetate in hexanes containing 2% glacial acetic acid
18. 18
    ConcentrationThe desired fractions were concentrated
19. 19
    Otheras several separate batches
20. 20
    Other1H NMRs were obtained
21. 21
    OtherThe solid was dried under high vacuum overnight
22. 22
    Filtrationfiltered
23. 23
    OtherThe resulting solid was dried in the vacuum oven at 60° C. for 24 h

Procedure

A solution of [4-(6-chloro-5-isopropyl-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid (9a) (0.10 g, 0.29 mol) in glacial acetic acid (3 mL) was treated with sodium acetate (54 mg, 0.65 mol) at room temperature. The reaction mixture was heated to 100° C. for 24 h. At this time, the reaction mixture was cooled to room temperature and was concentrated under vacuum. The resulting residue was diluted with water (100 mL), made basic by the addition of a 1N aqueous sodium hydroxide solution and was extracted with ethyl acetate (200 mL). The ethyl acetate layer was discarded. The water layer was acidified to pH=4 by the addition of a 1N aqueous hydrochloric acid solution and was extracted with ethyl acetate (2×200 mL). The organic layers were combined, washed with a saturated aqueous sodium chloride solution, dried with magnesium sulfate, filtered and concentrated under vacuum to afford a solid. The solid was dissolved in ethyl acetate by adding methanol to form a solution and it was absorbed onto silica and concentrated under vacuum. The preabsorbed solid was purified by column chromatography using silica gel eluted with 20% ethyl acetate in hexanes containing 2% glacial acetic acid. The desired fractions were concentrated as several separate batches and placed under high vacuum for 1 h. 1H NMRs were obtained to determine if batches contained only the desired isomer. The best batches were combined, diluted with a 1:1 methylene chloride:hexanes solution. This process was performed three times. The solid was dried under high vacuum overnight and then slurried in acetonitrile and filtered. The resulting solid was dried in the vacuum oven at 60° C. for 24 h to afford [4-(5-isopropyl-6-oxo-1,6-dihydro-pyridazin-3-yloxy)-3,5-dimethyl-phenyl]-acetic acid (10a) (61 mg, 65%) as a white solid; EI(+)-HRMS m/z calcd for C17H20N2O4 (M+) 316.1423, found 316.1427. Molecular Weight=316.3599; Exact Mass=316.1423

Source