反应详情

Aromatic fluorination of noscapine was achieved by employing the fluoride form of Amberlyst-A 26, a macroreticular anion-exchange resin containing quaternary ammonium groups. The method described [33] for Hal/F exchange may also be applied to other Hal/Hal′ exchange reactions. In Br/F exchange reactions, good yields were obtained only when a large molar ratio of the resin with respect to the substrate was employed. Thus, after refluxing a solution of bromonoscapine in anhydrous THF and an excess of Amberlyst-A 26 (fluorine, polymer-supported, 10 milliequivalents of dry resin; the average capacity of the resin is 4 milliequivalents per gram) for 12 hours, the resin was filtered off and the solvent was removed in vacuo to afford the desired compound (3) in 74% yield. The resin was recovered by washing with 1 N NaOH and then rinsing thoroughly with water until neutrality to generate the hydroxy-form of the resin. It was then stirred overnight with 1 N aqueous hydrofluoric acid, washed with acetone, ether and dried in a vacuum oven at 50° C. for 12 hours to afford the regenerated Amberlyst-A 26 (fluorine, polymer-supported), which can be reused.

1. additiona macroreticular anion-exchange resin containing quaternary ammonium groups
2. customIn Br/F exchange reactions, good yields
3. customwere obtained only when a large molar ratio of the resin with respect to the substrate
4. customfor 12 hours
5. filtrationthe resin was filtered off
6. customthe solvent was removed in vacuo