Dimethylformamide → HCID 13393786, Verbindung
Reaktionsgleichung
[C:1]([C:4]1[CH:5]=[C:6]2[C:11](=[CH:12][CH:13]=1)[O:10][CH:9]([C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1)[CH2:8][C:7]2=O)([OH:3])=[O:2].P(Cl)(Cl)([Cl:23])=O.CN(C)[CH:28]=[O:29]>>[C:1]([C:4]1[CH:5]=[C:6]2[C:11](=[CH:12][CH:13]=1)[O:10][CH:9]([C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1)[C:8]([CH:28]=[O:29])=[C:7]2[Cl:23])([OH:3])=[O:2]Komponenten
4
Versuchsvorschrift
As in example 1, but using 6 g 6-carboxy-flavanone, 60 ml dimethylformamide and 15 ml phosphorous oxychloride. Reaction time is three hours at 50° C. After hydrolysis a precipitate formed which is filtered, washed with water and dried over phosphorous pentoxyde. The residual solid is dissolved in a 10% sodium bicarbonate aqueous solution, which is then washed with methylene chloride. The aqueous phase is acidified with a 10% hydrochloric acid solution and the precipitate which formed is filtered, washed and dried. The residual solid is recrystallised in a mixture of hexane and ethyl acetate and pure 6-carboxy-4-chloro-3-formyl-flav-3-ene is obtained; m.p. 262°-267° C.