Reaction #410833

Reaction equation

NaBH4

7-Chloro-4-hydroxy-2-(4-methoxy-2-methylphenyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione

trifluoroacetic acid

NaBH4

→

title compound

Yield 39.4%

7-Chloro-4-hydroxy-2-(2′-methyl-4′-methoxyphenyl)-5,10-dihydro-2H-pyridazino[4,5-b]quinoline-1-one

Yield 39.4%

Solvents

tetrahydrofuran

Conditions

Workup

1. 1
   workup.WAITwas stored in a freezer overnight
2. 2
   workup.STIRRINGstirred at 0° C. for 2 hours
3. 3
   workup.ADDITIONThe reaction mixture was poured onto water (500 mL)
4. 4
   Extractionextracted with ethyl acetate (2×200 mL)
5. 5
   Concentrationconcentrated in vacuo
6. 6
   workup.ADDITIONThe residue was poured onto ether (400 mL)
7. 7
   Otherthe solid which formed
8. 8
   Filtrationwas collected by filtration
9. 9
   Otherto afford crude product
10. 10
    OtherThe crude was recrystallized from methanol

Procedure

7-Chloro-4-hydroxy-2-(4-methoxy-2-methylphenyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione (5.0 mL, 13.1 mmol) was suspended in tetrahydrofuran (170 mL) under nitrogen cooled to 0° C. and treated with trifluoroacetic acid (18 mL, 235 mmol). Over a 10 minute period, the reaction mixture was then treated with NaBH4 (1.973 g, 52.2 mmol). The reaction mixture was stirred at 0° C. for 6 hours and then was stored in a freezer overnight. The reaction mixture was then treated with additional NaBH4 (approximately 1.0 g) and stirred at 0° C. for 2 hours. The reaction mixture was poured onto water (500 mL) and extracted with ethyl acetate (2×200 mL). The ethyl acetate extracts were combined and then concentrated in vacuo. The residue was poured onto ether (400 mL) and the solid which formed was collected by filtration to afford crude product. The crude was recrystallized from methanol to afford 1.91 g of the title compound as an off-white solid, mp 264-266° C.

Source