2,3-Dibromopropene → 7-[(2-bromoallyl)oxy]-4-methyl-2H-chromen-2-one

Reaktionsgleichung

[CH3:1][C:2]1[C:11]2[C:6](=[CH:7][C:8]([OH:12])=[CH:9][CH:10]=2)[O:5][C:4](=[O:13])[CH:3]=1.[Br:14][C:15]([CH2:17]Br)=[CH2:16].C(=O)([O-])[O-].[K+].[K+]>CC(C)=O>[CH3:1][C:2]1[C:11]2[C:6](=[CH:7][C:8]([O:12][CH2:17][C:15]([Br:14])=[CH2:16])=[CH:9][CH:10]=2)[O:5][C:4](=[O:13])[CH:3]=1

Komponenten

Versuchsvorschrift

4-Methyl-7-hydroxycoumarin (2.00 g., 11.4 m mole) was refluxed with freshly-distilled 2,3-dibromopropene (2.72 g., 13.6 m mole), anhydrous potassium carbonate (3.15 g., 22.8 m mole), and acetone (80 ml.) for four hours. The reaction mixture was treated as described for the preparation of Example I, Part 1-A to obtain 4-methyl-7-(2'-bromoallyloxy) coumarin as an off-white solid (3.70 g.) that contained some excess 2,3-dibromopropene. Recrystallization of a portion (500 mg.) from ligroin (b.p. 100°-120° C.) gave needles (394 mg., 89% yield) of m.p. 109.5°-110.5° C. An analytical sample of m.p. 110°-111° C. was obtained by recrystallization from methanol.