Reaction #302856

Reaction equation

boron tribromide

compound 19

6-iodo-4′-methoxyflavone

→

compound 20

6-bromo-4′-hydroxyflavone

Solvents

dichloromethane

dichloromethane

Conditions

Workup

1. 1
   Temperatureunder cooling on ice
2. 2
   OtherAfter completion of the reaction
3. 3
   Otherpurified water (80 ml)
4. 4
   workup.ADDITIONwas added to the reaction solution
5. 5
   Extractionthe dichloromethane layer was extracted
6. 6
   DryingThe extract was dried over anhydrous sodium sulfate
7. 7
   workup.DISTILLATIONthe solvent was then distilled away under reduced pressure

Procedure

A dichloromethane solution (4.9 ml) that contained boron tribromide was slowly added to a dichloromethane solution (85 ml) that contained compound 19 (185 mg, 0.489 mmol) while stirring under cooling on ice, and the reaction was then carried out for 30 hours. After completion of the reaction, purified water (80 ml) was added to the reaction solution, and the dichloromethane layer was extracted. The extract was dried over anhydrous sodium sulfate, and the solvent was then distilled away under reduced pressure. The residue was subjected to silica gel column chromatography using ethyl acetate/hexane (1/4) as an elution solvent, so as to obtain a product of interest, 6-bromo-4′-hydroxyflavone (compound 20). Yield: 79 mg (yield constant: 44.3%) 1H NMR (300 MHz, DMSO6) 610.37 (s, 1H), 8.27 (s, 1H), 8.28-8.30 (m, 1H), 7.98 (d, J=8.4 Hz, 2H), 7.61 (d, J=8.7 Hz, 1H), 6.93-6.95 (m, 3H). MS m/z 364 (M+).

Source